New frontiers in laser interaction: from hard coatings to smart materials

Resume : Pulsed Laser Deposition (PLD) is widely used for the synthesis of valuable carbon-based thin films because of their capacity to present a combination of unique properties which can be tailored over a wide range. The efficiency of Pulsed Laser Deposition (PLD) process is related to the ability to control the ablation plume characteristics such as composition, excitation and kinetic properties of species The potential of laser pulses temporally tailored on ultrafast time scales is used to control the expansion and the excitation degree of ablation products, with in situ optical diagnostic of the ablation plume. The temporal laser pulse shaping is shown to strongly modify the laser-induced plasma contents and kinetics for graphite ablation which are discussed in terms of modification of the structural properties of deposited Diamond-Like Carbon films (DLC) [1]. This gives rise to a better understanding of the growth processes involved in fs-PLD and ps-PLD of Diamond-Like Carbon. The Pulsed Laser Deposition also proved efficient to produce multilayer graphene for applications in the domain of biosensors. We report a new way to synthesize large scale 3D textured graphene by pulsed laser deposition with very good SERS [2] or electrochemical properties [3]. Nitrogen doping appears as an interesting option to modify the properties of graphene. N-doped graphene synthesis is also reported with mainly pyridinic- type of nitrogen bonding. References [1] F. Bourquard, T. Tite, A.-S. Loir, C. Donnet, F. Garrelie, “Control of the Graphite Femtosecond Ablation Plume Kinetics by Temporal Laser Pulse Shaping: Effects on Pulsed Laser Deposition of Diamond-Like Carbon”, The Journal of Physical Chemistry Part C 118(8), 4377-4385 (2014) [2] T. Tite, C. Donnet, A. –S. Loir, S. Reynaud, J. –Y. Michalon, F. Vocanson, V. Barnier, F. Garrelie, “Surface enhanced Raman spectroscopy platformbased on graphene with one-year stability”, Thin Solid Films 604 (2016) 74-80 [3] P. Fortgang, T. Tite, V. Barnier, N. Zehani, C. Maddi, F. Lagarde, A.-S. Loir, N. Jaffrezic-Renault, C. Donnet, F. Garrelie, C. Chaix, “Robust electrografting on self-organized 3D graphene electrodes”, ACS APPLIED MATERIALS & INTERFACES, 8(2) (2016) PP 1424-1433

Resume : Low-cost and high-throughput manufacturing of functional thin film nanomaterials has attracted more and more interest due to the demands for non-fossil energy and portable and wearable electronics. However, traditional physical and chemical processes do not support the cost-efficient manufacturing. Pulsed photonic irradiation or flash photonic curing using a PulseForge system has shown great potential in manufacturing printable and flexible electronics. The PulseForge technology uses a computer to control the pulse train of a pulsed Xe lamp which emits mostly as visible light. It has been used for photonic curing of printed polymer and hybrid dielectric films on flexible substrates [1,2] as well as photonic sintering the printed metal electrodes on polymer substrates. There are two traditional mechanisms to rapidly process thin film materials: for polymers, similar to UV curing, a radiation-induced polymerization occurs; for metal and inorganic nonmetallic materials showing high attenuation of light, the large photothermal conversion rate results in internal heating of the materials. The PulseForge processing of nanostructured metal oxides thin films with a large specific surface area are preferable for practical device applications in energy conversion and storage. Herein we demonstrate a novel approach to the instantaneous (milliseconds) photoinitiated synthesis of 3-D nanostructured metal oxides thin films through the pulsed photoinitiated pyrolysis accompanied by instantaneous self-assembly and crystallization processes, which are achieved through pulsed photonic irradiation (xenon flash lamp, pulse width of 1.93 milliseconds, fluence of 7.7 J/cm2 and frequency of 1.2 Hz) of photosensitive metal-organic precursor films made by chemical solution deposition. Subsequent pulses rapidly (within a couple of minutes) improve the crystalline quality of nanocrystalline metal oxides thin films through pulsed photothermal effect. The demonstrated processing is applicable to fabrication of TiO2 [3], Co3O4 [4], Fe2O3 and other metal oxides. This photoinitiated nanofabrication technology opens a promising way for the low-cost and high-throughput manufacturing of nanostructured metal oxides thin films. References [1] B. C. Riggs, R. Elupula, S. M. Grayson, and D. B. Chrisey. Photonic curing of aromatic thiol-ene click dielectric capacitors via inkjet printing. J. Mater. Chem. A, 2, 17380 (2014) [2] B. C. Riggs, R. Elupula, C. Rehm, S. Adireddy, S. M. Grayson, and D. B. Chrisey. Click-in ferroelectric nanoparticles for dielectric energy storage. ACS Appl. Mater. Interfaces, 7, 17819 (2015) [3] S. Luo, S. Zhang, B. B. Bourgeois, B. C. Riggs, S. Adireddy, K. A. Schroder, Y. Zhang, J. He, K. Sun, J. T. Shipman, V. Puli, R. Tu, L. Zhang, S. Farnsworth and D. B. Chrisey. Instantaneous photoinitiated synthesis and rapid pulsed photothermal treatment of three-dimensional nanostructured TiO2 thin films through pulsed light irradiation. Submitted to Journal of Materials Research, (2017) Invited paper [4] S. Luo, W. Liu, G. Moses, B. Briley, J. He, B. C. Riggs, S. Adireddy, J. Shipman, S. Zhang, L. Zhang, N. Pesika and D. B. Chrisey. Photoinitiated synthesis of Co3O4-reduced graphitic oxides in-situ nanocomposite thin film as electrode materials for silicon-based micro-supercapacitor with ultra-long lifetime. Submitted to Nano Lettters, (2017)

Resume : One of the biggest challenges that flat panel display technologies but also various optoelectronic and photovoltaic devices will be to face in the forthcoming years is to find an alternative to the use of transparent conducting oxides (TCO) like ITO. Diamond-Like Carbon (DLC) films as substrate prepared by Pulsed laser deposition (PLD) have attracted special interest due to a unique combination of their properties, close to those of the monocrystalline diamond, like transparency, hardness and chemical inertia, very low roughness, hydrogen-free and thus high thermal stability up to 1000 K. In our recent work, we explore the synthesis of conductive Thin-Layer Graphene (TLG) on the top of insulating DLC thin films. The feasibility and obtained performances of the multilayered structure is currently explored in great details in order to develop an alternative to ITO with comparable performance (conductivity of transparency). In this paper, we focus on the physicochemical properties of the DLC thin films deposited by PLD from a pure graphite target at two wavelengths (193 and 248 nm) and at various laser fluences. The surface graphenization process as well as the required efficiency of the complete structure (TLG/DLC) will be clearly related to the DLC properties, especially to the initial sp3/sp2 hybridization ratio. Thus, an exhaustive description of the physicochemical properties of the DLC layers is a fundamental step in the research of comparable performance to ITO.

Resume : It is well known that Pulsed Laser Deposition (PLD) is a very flexible and versatile technique allowing fast optimization of new and complex material thin films. The unique features of PLD allow for the integration of “Beyond Moore” materials in CMOS and new devices. However, mainly because of the sample size, the developed materials and processes in PLD research tools only just make it into demonstrator devices. In order to make it into commercial applications, next generation PLD equipment is needed to bridge the gap between demonstrator and the prototype – pilot – production stages. The Solmates PLD platform is the next step beyond fundamental PLD research. The reliable hardware is flexible for fast process optimization and allows uniform thin film deposition up to 200 mm diameter with high reproducibility. The automated software ensures easy operation and stable performance. These characteristics enable the integration of PLD thin films in applications for (pilot) production and commercialization. In this contribution the latest performance and specifications of Solmates PLD platform are addressed. Data on stability and reproducibility of wafer scale deposition of PZT thin films with excellent properties will be presented. Furthermore, two qualified processes Indium Tin Oxide and Aluminum Oxide thin films will be used to show some key capabilities of PLD such as damage free deposition on organic electronics or control of thin films density and microstructure for optical or sensing applications.

Resume : Experimental investigations were performed on laser produced plasma generated by nanosecond, picosecond and femtosecond laser ablation on metallic targets (Mn, Ni, Cu, Zn, Ti and Al). The aim of this work was to investigate the effect of the target physical properties (electrical and thermal conductivities, melting, boiling points etc.) on the plasma plumes dynamics. The experiments were performed in similar conditions of laser fluence (8.7-10 J/cm2) background pressure (p = 10-5 Torr) and probe-target axial distances (d = 1 - 40 mm) for all the investigated targets. Time-resolved optical investigations were focused on recording snapshots of the laser-produced plasmas at different time delays with respect to the ablation laser pulse, in order to investigate the structure of the plasma plumes and their global dynamics. The electrical investigations were performed by means of Langmuir probe method, which consists of immersing an electric probe in the plasma volume and extracting the electronic or ionic currents. By sampling the ionic and electronic temporal traces and reconstructing the I-V characteristics at different moments during plasma expansion, we were able to determine the temporal evolution of various plasma parameters which present different behaviors for the plasmas produced in ns, ps and fs regimes. In order to obtain information about the dynamics of the ejected ions, the ionic current is discussed in terms of a shifted Maxwell-Boltzmann distribution function, offering the possibility to determine parameters such as the drift velocity and the ion average temperature. Some plasma parameters were found to be dependent on the target physical properties. In particular, a strong connection was found between the electrical conductivities of the targets and the electron temperature. These results represent a base for future experimental and theoretical studies that will allow us to comprehend the targets properties influence over the laser produced plasma plumes formation mechanisms and evolution.

Resume : Laser surface modification can be used to enhance the mechanical properties of a material, such as hardness, toughness, fatigue strength, and corrosion resistance. Surface nitriding is a widely used thermochemical method of surface modification, in which nitrogen is introduced into a metal or other material at an elevated temperature within a furnace. It is used on parts where there is a need for increased wear resistance, corrosion resistance, fatigue life, and hardness. Laser nitriding is a novel method of nitriding where the surface is heated locally by a laser, either in an atmosphere of nitrogen or with a jet of nitrogen delivered to the laser heated site. It combines the benefits of laser modification with those of nitriding. Recent work on high toughness tool steel samples has shown promising results due to the increased nitrogen gas impingement onto the laser heated region. Increased surface activity and nitrogen adsorption was achieved which resulted in a deeper and harder surface compared to conventional hardening methods. In this work, the effects of the number of laser passes, laser power, laser wavelength, and gas mixtures will be presented. Resulting microstructure, phase type, and microhardness in particular are presented.

Resume : Following our work on the repassivation mechanism[1,2] as a time-dependent linear combination of a high-field model of oxide growth (HFM)[3] and the point defect model (PDM)[4] we present our findings on the laser-induced thin-film formation on aluminium via two concurrent charge consumption channels, providing hints for a unified theory describing the passivation process from the blank metal to the steady state. For that, in situ nanosecond-pulse-laser depassivation[4,5] of plasma electrolytically oxididized (PEO) coatings on aluminium was performed under potentiostatic control and the resulting charge flow for oxide-film formation was analyzed. We find that the charge contribution of the HFM supersedes the one of the PDM with proceeding increase in layer thickness, pointing to subsequent defect-centre annihilation from the bare metal to passivity. A pulsenumber dependent increase and saturation in relative weight of the PDM-channel is observed with which can be attributed to thermo-mechanical strain correlated defect formation (incubation) by the laser itself. [1] T.O. Nagy, M.J.J. Weimerskirch, U. Pacher, W. Kautek, Z. Phys. Chem. 230 (2016),1303–1327. [2] T. O. Nagy et al., Appl. Surf. Sci. 302 (2014) 184-188. [3] T.P. Hoar et al., J. Phys. Chem. Solids 9 (1959) 97-99. [4] D. D. Macdonald, J. Electrochem. Soc. 139 (1992) 3434-3449. [5] A. Cortona and W. Kautek, Phys. Chem. Chem. Phys. 3 (2001) 5283-5289. [6] W. Kautek and G. Daminelli, Electrochim. Acta 48 (2002) 3249-3255.

Resume : Laser-induced backside wet etching (LIBWE) is a promising approach for precise micro machining on transparent materials. The LIBWE method relies on the focusing of the pulsed beam at the solid thin film and the absorbing liquid interface causing etching on the backside of the transparent material. LIBWE with nanosecond lasers on materials such as fused silica have been extensively researched. However, little research has focused on the use of PMMA, a widely used material for microfluidic devices such as disposable biomedical sensors and lab-on-chip. LIBWE of PMMA with nanosecond lasers at wavelength 1064 nm with InGa absorbing liquid is used for the first time. The influence of pulse repetition rate, laser fluence and pulse energy to the surface morphologies were examined. The surface characteristics were examined by scanning electron microscopy (SEM) and surface profilometry. The maximum depth was found to be 8 µm and results suggest LIBWE is suitable for producing high surface quality etching on PMMA.

Resume : TiO2 is a strategic material in heterogeneous catalysis, photo-assisted oxidation, optical and photovoltaic devices. The efficiency of such processes could be increased by synthesizing fractal materials with nano- and mesoscopic pores, or by hierarchical organization of nanostructures. Pulsed laser deposition (PLD) in the nanosecond (ns) regime is known to obtain nanoparticles (NP) either in low high or ultra-high vacuum and even in liquid. Femtosecond (fs) PLD is inducing target non-thermal ablation, and laser fluence, sample-target distance and environment pressure influence the properties of the deposited material. However very little is known about TiO2 nanostructure formation at ambient pressure. In this work we obtain fractal TiO2 nanostructures in crystalline form at room temperature by ambient pressure fs-PLD. The structures are composed by both rutile and anatase NP with an average diameter smaller than 20 nm. The fractal dimension depends on the density of deposited material, while the size distribution of the fractals and NP depends on laser fluence and sample/target distance. We discuss the role of substrate conductivity and roughness in the fractal formation through Monte Carlo simulations of NP diffusion onto different substrates. The model allows to predict the fractal dimension and area distribution for tailoring the synthesis of fractal nanostructures by PLD. E. Cavaliere et al. J. Phys. Chem. C 117 (2013), 23305 G.L. Celardo et al. Mat. Res. Express (2017)

Resume : Ultrashort pulsed laser glass welding is a method developed by research teams recently adapted to industrial processes. This industrialization will be beneficial for different applications such as microfluidics or microelectronics. The method presents many advantages compared to other glass bonding techniques such as adhesive or anodic bonding: absence of adhesive material, high process speed, transparency, thermal, mechanical and chemical resistance, and the ability to bond materials with different thermal coefficients. The study focuses on the induced residual stress in order to minimize it and to improve the welding tensile resistance and preserve the glass optical properties. Welded seams in borosilicate glass are created with a femtosecond fiber-laser generating 300 fs duration pulses at 500 kHz repetition rate. At high repetition rate, despite the ultrashort pulse duration, our simulations show a thermal accumulation effect increasing the material temperature at every pulse until the melting point. In contrast with most of the recent work using a microscope objective inducing very high thermal peak, the laser beam was focused with an f-theta lens integrated in a scanner head. Our focused beam diameter is larger, avoiding high temperature peak, which is expected to reduce the thermal stress. Residual stress mapping by photoelasticimetry is studied as a function of the process parameters and can be optimized by adapting the welding seam patterns and laser parameters.

Resume : The production of clean colloidal solutions of nanoparticles (NPs) through pulse laser ablation in liquids (PLAL) has evolved into a mature research field with a large number of applications. While challenges of increasing productivity and broadening the range of materials for which NPs can be generated are successfully addressed by recent developments, the goal of achieving narrow NP size distributions by one-step PLAL still remains elusive. In particular, bimodal size distributions, where the desired small NPs coexist with larger (tens to hundreds of nanometers) ones, are commonly observed in PLAL experiments. In this presentation, we report the results of large-scale atomistic simulations aimed at revealing the mechanisms of NP formation in PLAL and explaining the origin of the bimodal size distribution. Two distinct mechanisms of the NP formation are predicted in the simulations: (1) the nucleation and growth of small (mostly ≤ 10 nm) NPs in the metal-water mixing region and (2) the formation of larger (tens of nm) NPs through the breakup of a superheated molten metal layer triggered by Rayleigh-Taylor instability of its interface with supercritical water. The insights into the mechanisms of the NP formation may help in designing approaches aimed at minimizing the fraction of large NPs.

Resume : Formation mechanisms of the laser-induced periodic surface structures (LIPSS) are controversially discussed since their first observation in 1965 until nowadays. Some arguments support the theory of plasmonic origin of the observed surface patterns, some speak for hydrodynamic nature of LIPSS. In this talk we combine these two theories, and figure out to what extent the surface scattered waves influence the LIPSS formation and what are possible hydrodynamic processes in the melt. We analyse mechanisms, which can be responsible for the appearance of periodic patterns during three following steps of femtosecond laser ablation of metals, which are: (1) electron heating by the incident wave; (2) energy transfer from the electrons to the lattice; (3) melting and solidification of the surface layer. We show that all these three steps are equally important for femtosecond LIPSS formation and confirm the suggested model with experiments on the LIPSS generation at different wavelengths of the incident light.

Resume : The mechanism of materials surface restructuring by ultrashort laser pulses involves a lot of fast, non-equilibrium, and interrelated processes while the solid is in a transient state. Former theoretical methods cannot address all the aspects regarding the nanostructuring mechanisms contained in the experimental results. In this work, we propose a combined atomistic-continuum approach suitable for investigation of periodic nanostructuring mechanism due to a UV ultrashort laser pulse. In this model the kinetics of laser-induced phase transitions is addressed at atomic scale while the processes of laser light absorption, fast electron heat conduction, and strong electron-phonon non-equilibrium are described in continuum. The model is applied to investigate the mechanism of nanostructuring on a gold surface for the case of both vacuum ambient and under regime of spatial confinement due to a thick water layer. The experimental results were obtained by using a mask projection setup with a laser wavelength of 248 nm and a pulse length of 1.6 ps. This setup is used to produce an intensity grating on a gold surface with a sinusoidal shape and a period of 270 nm. The experimental and theoretical results are compared directly on the same temporal and spatial scale. The good agreement between the modeling results and the experimental data justifies the proposed approach as a powerful tool revealing the physics behind the nanostructuring process at gold surface and on metals in general.

Resume : Femtosecond laser pulses can be used to manipulate solids beyond thermodynamical limitations. To model laser material processing on the nanoscale by means of large scale simulations one needs to consider a huge number of atoms (of the order of 100 000 000). Such simulations can only be performed using a classical analytical interatomic potential. Such a potential must contain information about nonthermal effects due to the presence of hot electron-hole pairs excited by the laser. Here, we present a method for developing potentials from ab-initio molecular dynamic simulations, that can accurately describe thermal and nonthermal effects occurring after an intense femtosecond laser excitation. In detail, we performed extensive density functional theory MD simulations of the laser excitation of silicon in thin film geometry and antimony in the bulk and developed potentials for both materials by combining force- and energy matching approaches. The shape for both potentials is intuitive and easy to implement numerically and contains embeded-atom as well as two- and three body interatomic terms. This potential reproduces the cohesive energy, atomic forces, phonon band structures and elastic constants after the laser excitation. In addition, effects like bond-softening, fractional diffusion and nonthermal melting are well reproduced.

Resume : We propose a method for analyzing the elemental composition of isolated nanoparticles. It is based on Laser-Induced Breakdown Spectroscopy (LIBS). LIBS allows remote specific detection of most of the chemical elements in a sample and at very low concentrations. We propose a new experimental setup in which we perform the laser-particle interaction in vacuum, on a single nanoobject. A small part of the aerosol stream is sampled and driven to an aerodynamic lens system. The latter produces a dense and collimated beam of nanoparticles under vacuum from the atmospheric pressure aerosol flow. The photon signal from the plasma is collected by an UV-compatible optical fiber connected to a spectrograph. As the interaction takes place at low pressure, the photons are emitted only from particles. Unlike previous experiments, the background from interaction with the gaseous component is totally eliminated. Moreover, as the nanoparticle beam is highly collimated, the optical interfaces are not obstructed by particle deposition and the system can be kept running for hours. This method can also be adapted to any particle samples in a stable suspension.

Resume : The development during the last decades of laser micro-sampling techniques led to analysis of increasingly limited area of biological material. Combined to the use of mass spectrometers with increased sensitivity, it allows the identification of biomarkers of interest at a spatially-resolved scale. In general, laser micro-sampling requires the use of a wavelength that can efficiently excite the molecules present in the investigated system (matrix or analytes). However, a recent study [1] has demonstrated that biomolecule analysis of native samples, without any addition of matrix, is possible using =532 nm even at low laser energy through an indirect substrate-mediated laser ablation (SMLA) mechanism, although the absorbance of biomolecules at this wavelength is low. Systematic studies taking into account the physico-chemical parameters of various substrates highlight the role of the ablation of the substrate in the origin of the micro-sampling of the tissue. Afterward, taking advantage of this SMLA effect to increase the spatial resolution and reduce delivered energy, we perform large-scale proteomic analyses of micro-sampled tissue sections and demonstrate the possible identification of proteins and lipids by mass spectrometry.

Resume : Bulk hybrid materials (HM?s) based on inorganic glass matrix of the composition 80 (mol.%) PbF2-20 (mol.%) B2O3 and various organic phosphors (complexes of 8-hydroxyquinoline with I, II, III groups metals of the Periodic Table and lanthanide phenanthroline complexes) is established to show efficient photoluminescence (PL) at phosphor contents about 0.1 wt% in the matrix?s. Partial HM's crystallization led to the increase of PL intensities in 1.5-5 times. Local crystallization of HM's stimulated by femtosecond laser beam allowed to create 3D integrated optics elements. PbF2 crystallites formed inside HM had lower refractive index as compared to the glass matrix. HM-based samples with locally controlled PL were fabricated by Pharos SP laser (wavelength 1030 nm, pulse duration from 180 to 5000 fs, frequency repetition from 1 to 1000 kHz, maximum power 6 W). The samples demonstrated the increase in PL towards the initial HM's and waveguide effect in the laser-modified regions. The research was financially supported by Russian Science Foundation (grant N 14-13-01074)

Resume : Bismuth-germanium oxide glasses are transparent in visible and near-IR spectral regions and therefore they may be applied as matrixes for rare-earth and transition ions doping. By heat treatment, it’s possible to crystalize several phases in these glasses, namely, scintillating phase Bi4Ge3O12 and ferroelectric phase Bi2GeO5. A variation of the initial oxides ratio in glass leads to crystallization of either a single phase or several phases’ mixture. The same effect is also achieved by variation of heat treatment conditions. To obtain enhanced ferroelectric properties it’s preferably to get crystallites oriented along one direction in a glass matrix. It’s well known that textured glass-ceramic materials can be successfully produced by a laser treatment. In the present research, different composed bismuth-germanium oxide glasses doped with chromium were treated by a femtosecond Pharos SP laser (wavelength 1030 nm, pulse duration from 180 to 5000 fs, frequency repetition from 1 to 1000 kHz, maximum power 6 W). The structure and morphology of induced crystal phases as well as the laser treatment conditions affect on crystallization process were investigated by XRD and SEM. The research was financially supported by Russian Science Foundation (grants 14-13-01074 and 16-03-00541)

Resume : Femtosecond (fs) laser processing of glass is widely studied for various applications, including the fabrication of photonic devices[1]. Although many interesting results have been obtained[1, 2], to fully benefit from direct fs laser processing of glass, further experimental and theoretical results are needed. This work focused on the experimental study of fs laser processing of silica glass embedded with gold and lead oxides. The Ti:sapphire laser (800 nm, 100 fs, 1kHz) has been used to write lines onto the glass. A clear change of the glass color has been obtained when adequately illuminated (i.e. in the case of intense exposure of the order of 300 mW, at 800 nm, with laser beam focused inside the glass). The glass previously transparent become yellowish almost instantaneously. We showed that thermal annealing leads to erasing the previous colored area, which can be still colored by a new step of irradiation. The mechanism of this reversible modification is in progress. It is worth to notice that focusing the laser beam at the glass surface was not effective for coloring, but leads to the formation of perfect micrometer-slits. Potential applications of our study is to fabricate waveguide-based photonic devices, or rewritable optical devices, among other. [1] Rafael R. Gattass and Eric Mazur, Nature Photonics 2, 219-225 (2008) [2] Katherine C. Phillips, Hemi H. Gandhi, Eric Mazur, and S. K. Sundaram, Advances in Optics and Photonics 7, 684-712 (2015)

Resume : Until the end of the 1980s many wooden artworks underwent surface treatment by liquid preservatives, e.g. Hylotox-59. As a result, DDT (dichlorodiphenyltrichloroethane) crystal structures are formed on the wood surfaces by the "blooming" of chlorine compounds. In addition to an aesthetic disturbance, it is assumed that DDT represents a health risk. Even decades after applying, the toxins in the wood preservatives are still detectable. Contaminated waste wood with natural biocide ageing, gilded and wood carved elements of an old picture frame and wooden samples with paint layers were provided by the Schlossmuseum Sondershausen, Germany. Laser cleaning of areas of some square millimeters on the surfaces of the objects was done by means of femtosecond and nanosecond laser pulses. For 30-fs laser pulses at 800 nm wavelength a line-wise meandering movement of the object under the focused beam was performed. 10-ns laser pulses at 1064 nm and 7-ns laser pulses at 532 nm wavelength were applied to the sample surface using a scanner. Before laser application, a chlorine measurement was done by X-ray fluorescence analysis (XRF) as reference. After laser processing, the XRF analysis was used again at the same surface position to determine chlorine depletion rates of up to 75% (30 fs, 800 nm), 70% (10 ns, 1064 nm), and 22% (7 ns, 532 nm). For the application of 30-fs laser pulses on waste wood, no crystalline DDT residues remain on the sample surface observed utilizing optical microscopy.

Resume : Laser welding of polymer materials is an increasing and potential activity for different industrials. We propose a study of laser welding polymer plates or sheets with high power infrared diodes. One transparent plate is employed to bring the laser beam to the interface. A second absorptive polymer is placed in contact with the first transparent polymer. The principle is to focalize the infrared laser beam at the interface; the second polymer absorbs, heats up and transmits the heat by contact to the first polymer. In this application, the main constraints are the spectrum window of the polymers and the quality of the thermal contact between the two polymers. We realize a thermal simulation with Comsol to demonstrate the principle of this welding effect and to see the temperature level between the interface of the two polymers. Analysis of strains and SEM Image at the interface shows us clearly the thermal affected zone: one can identify the best laser parameters for the welding effect with these measurements. In the same way, post-processing the images of the welding zone by camera can lead to a rejection threshold for poor welding results. FTIR measurements was also employed to demonstrate the change of polymer structure at the interface.

Resume : In order to obtain copper films from CuSO4 solution and improve film adhesion to CdTe crystals we carried out laser irradiation of the samples by millisecond YAG laser. The aim was to create and optimize mechanically reliable, ohmic electrical contacts to CdTe and Cd1-xMnxTe crystals. The study of the morphology and structure of Cu thin films, formed after laser treatment, was carried out by SEM, AFM and transmission electron microscopy. Melting of the surface was observed at laser pulse power density of 10-15 J/cm^2 as the result of redistribution of energy between environment, Cu film and CdTe crystal. It was found different changes of morphology and structure of the copper film depending on defocusing of the laser beam. The structure of the film in the form of concentric closed circles is caused by propagation of surface waves in the liquid phase of the melt. Ablation of copper takes place in the center of the laser light spot at the maximum temperature of the processes, that follows in the formation of unequal shaped craters. More optimal morphology of the copper film was obtained by an action of out of focus laser beam. A continuous solid Cu film that has strong adhesion and provides reliable solder wire contacts is formed in CdTe and Cd1-xMnxTe crystals. AFM studies showed that crystallites of the film have rounded triangle shape which size decreases slightly from the middle to the periphery of the laser spot from 1-1.3 to 0.5-0.8 microns.

Resume : Lightpipe technology is widely employed for different non-imaging applications and for uniform illumination on large surface. We demonstrate the use a tapered lightpipe to allow a uniform illumination with a high power laser beam as incident light. The need of uniform illumination in laser material processing can be found in the field of welding system, marking system, surface texturing or additive fabrication. Several simulations were made on Zemax Opticstudio 16 with the non-sequential mode demonstrating the principle of beam shaping. Unlike other optical systems, one can choose any sources and it is thus possible to change a gaussian profile into a top-hat profile. The cost of our tapered lightpipe is much lower than other optical systems such as diffractive optics or complete refractive systems. Also, the component is simple to use and very flexible to obtain different type of shape for laser material processing. Moreover, the component can withstand high power. Our experience in this field allows us to propose many possible combinations for different lasers. A comparison with experiments in the case of infrared laser source confirms the choice of the right parameters.

Resume : In this work results on laser processing of thin metal and oxide films deposited on paper are presented. Au, Ag, Cu, Ni, and ZnO films are deposited by classical pulsed laser deposition method on glossy and standard printer paper. The produced films are then processed by nanosecond pulses delivered by Nd:YAG laser system. The laser processing parameters are varied and their influence on the film modification is presented. It is shown that at certain conditions the laser treatment of the films leads to formation of a discrete nanostructure, composed of spherical like nanoparticles. The structure and morphology of the fabricated samples are presented and discussed. Results on the use of these structures in Surface Enhanced Raman Spectroscopy are also presented. The demonstrated method is an alternative way for fabrication of metal and oxide nanostructures with application in low cost sensor devise fabrication.

Resume : This work deals with experimental study of Laser Induced Periodic Surface Structures (LIPSS) formation on polymer (polystyrene and poly(α-methylstyrene)) thin films (60-200nm) prepared by spin coating of polymer solutions deposited on silicon substrates. UV (266 nm) femtosecond laser beam (100 fs) is used at 1kHz for the polymer surface irradiation. Different structures are generated depending on the laser dose. Ripples presenting a period in the range of 40 to 260 nm typically High Spatial Frequency LIPSS (HSFL) and Low Spatial Frequency LIPSS (HSFL) are formed at relatively very low fluence (5 mJ/cm²) and high number of pulses (up to 10000 pulses). Also, Original 2D droplets (150 nm of diameter) organized in well periodic hexagonal pattern are observed by scanning electron and atomic force microscopies. Furthermore, the formation mechanisms of these nanostructures are discussed and compared to the findings reported in literature. It is found that free-surface energy minimization through the relaxation of hydrodynamic instabilities model could match well with our experimental results.

Resume : Printed electronics appears from the need to easily manufacture electronic circuits away from the silicon technology and with low production costs. Among the most extended printing techniques, such as lithography or screen printing, inkjet printing is characterized for being digital, since patterns can be drop-to-drop printed on demand. However, there are some limitations concerning the rheology of the liquid to transfer that limit the particle size and viscosity of printable inks. Laser-induced forward transfer (LIFT) appears as an interesting alternative since it is free from those constraints. In LIFT, a liquid film of the material to transfer is first spread along a donor substrate which is separated a convenient gap from a receiver substrate. Then, through the action of a laser pulse focused on the donor film a bubble is induced and as it expands a jet is propelled forward. Finally, as it reaches the receiver a droplet is deposited. Through the repetition of this process lines and patterns can be easily transferred. The aim of this work is to study the LIFT of conductive inks on flexible substrates similar to those used in roll-to-roll manufacturing. We first investigate the optimum transfer conditions by performing a systematic variation of the main process parameters, and then prove the feasibility of the technique to print on flexible substrates, thus showing its potential for printed electronics applications.

Resume : Optical, Thermal and Structural analysis of copper and titanium thin films (with 200 nm the thickness) are achieved by applying accumulative pulses. Namely, the thermal properties are investigated by a pulsed photo-thermal technique (PPT). The reflectivity changes are identified by a Real Time Reflectivity (RTR) method. The principles of RTR and PPT methods under hemispherical reactor were previously discussed in [1,2]. The sample is irradiated (heated) under atmospheric pressure or vacuum by a homogenized excimer laser beam (248 nm, 27 ns, 10Hz). The heated sample emits infrared radiations from its surface which are focused by two off-axis paraboloid mirrors into the IR detector (liquid-nitrogen-cooled HgCdTe photovoltaic photodiode). The obtained signal is then recorded on a digital oscilloscope (500 MHz). With RTR method, a He-Ne laser (633 nm, 15mW) is used for probing. The reflected signals are measured using very fast photodiodes. Moreover, surface morphology change is also analysed by Scanning Electron Microscopy (SEM). Discussion of the reflectivity and the thermal properties changes on copper and titanium thin films is detailed with respect to the laser beam parameters : fluence (20 - 200mJ/cm2) and the number of laser shots (N=1-10000) and the thin film surface properties (roughness, IR emissivity...). Reference: [1] N. Semmar, M. Tebib, J. Tesar, N.N. Puscas, E. Amin-Chalhoub, Applied Surface Science 255 (2009) 5549. [2] K. Ait Aissa, N. Semmar, A. Achour, Q. Simon, A. Petit, J. Camus, C. Boulmer-Leborgne, M. A. Djouadi, J ; Phys. D : Appl. Phys. 47 (2014) 355303.

Resume : Laser Induced Periodic Surface Structures (LIPSS) are formed in polymers by irradiation with a linearly polarized laser beam at fluences below the ablation threshold. Such structures have a spatial period close to the laser wavelength and align parallel to the polarization of the laser beam. It has been demonstrated that carbon based compounds, namely expanded graphite (EG) and single wall carbon nanotubes (SWCNT), have become excellent fillers to reinforce polymers in order to improve some of their properties such as mechanical resistance and electrical conductivity. In this work, the formation of LIPSS by irradiation with a Q-Switched Nd:YAG laser (266 nm, 8 ns) was studied in films of poly(ethylene terephthalate) (PET) and PET/EG, and poly(trimethylene terephthalate) (PTT) and PTT/SWCNT. The morphology of the polymer films was characterized by atomic force microscopy, while surface properties were studied by the colloidal probe technique, which provides information about adhesion forces, by contact angle measurements using different liquids in order to determine the surface energies, and by Raman spectroscopy to inspect possible chemical modifications in the materials upon irradiation. Results show a dependence of the LIPSS properties on the carbon nanoadditive content and an increase of the hydrophilic character of surfaces after irradiation. Moreover, the polar component of the surface energy changes significantly and adhesion force increases.

Resume : Investigation of the basic mechanisms and their role in the removal of the irradiated material was based on a hybrid continuum - atomistic model including kinetics of both heterogeneous and homogeneous phase transformations in metal (Al) film under unsteady pico - nanosecond laser irradiation. The temporary shape of the laser pulse was set as a Gaussian curve. The results of molecular dynamics simulations have shown that the mechanisms of material removal by ps- pulse and ns- differ qualitatively. In the ps range main mechanism is a mechanical spalling in the unloading wave, while in the ns - are the main explosive boiling and spinodal decomposition. At high intensity values in both exposure modes is implemented mechanism of supercritical expansion. Was find out strong relationship between heterogeneous and homogenous phase transitions. Accounting for the effects of nonstationarity of laser exposure showed the presence of several ablation mechanisms pass into each other during a single pulse.

Resume : Considers the processes of ns-laser ablation of metal targets in the surrounding ambient gas. Used laser pulses had a duration of a few tens of nanoseconds and the energy of fluence of several J/cm2. The processes in target described in the framework of a hydrodynamic model with two moving interfaces that take into account the kinetics of heterogeneous melting-crystallization and evaporation-condensation mechanisms. For evaporated material and ambient gas were used radiation gas dynamics model and collisional-ionization radiation model written in the approximation of local thermodynamic equilibrium. Modeling has allowed to define the behavior, and the most important characteristics of the evaporated material expanding in the surrounding gas, including: plasma formation thresholds, depending on the duration and fluence of laser pulse, spatial and temporal distribution of temperature, density and pressure in the condensed and gaseous media, the velocity of propagation of shock waves, contact discontinuities and interphase interfaces, and charge composition of the plasma. Were investigated thermal and gas-dynamic effect of the plasma on ablation of the target and defining role in large time intervals (in comparison with the pulse duration) of radiation plasma flows in the expansion of the plume. The simulation results are compared with experimental data and calculations of other authors.

Resume : 2D material processing with high accuracy and reproducibility represents an emerging technology with great potential in applications aiming at the fabrication of micro- components, in particular flexible sensing devices. Successful highly sensitive material printing requires several technological developments, i.e. a combination of laser system benefits with the flexibility of polymer material design which ultimately lead to the creation of reproducible patterns with micro and nano precision. In this work, our latest advances on the laser-induced forward transfer (LIFT) process assisted by a triazene polymer (TP) layer for the spatial transfer of carbon nanotubes (CNTs) and CNTs decorated with Pt nanoparticles (Pt NPs) is presented. Specifically, the following issues will be addressed: i) CNT and Pt decorated CNT materials are transferred, with a transfer yield of nearly 100%, to fabricate chemical sensors; ii) the performance, i.e. the sensitivity, resolution, and response time of the laser-printed flexible sensor devices was evaluated by exposure of the sensors to different toxic vapors. Different sensitivities and selectivity to the selected analytes i.e. acetone, ethanol, ammonia, NO2, etc. have been measured thus proving the feasibility of LIFT for applications in flexible sensing devices. Acknowledgements This work was supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS – UEFISCDI, project number PN-II-RU-TE-2014-4-2311 and a grant from the Commission for Technology and Innovation CTI (project no. 16713.1 PFNM-NM).

Resume : In this work results on laser assisted formation of gold nanoparticles in glass are presented. The sample material is gold ion doped borosilicate glass obtained by conventional melt quenching method. The produced glass samples are irradiated by laser pulses with femtosecond and nanosecond duration. At certain conditions femtosecond laser radiation induces defects associated with formation of color centers in the material. After annealing of the samples the irradiated areas express red color with clear dip in the transmission spectra. This effect is related to formation of gold nanoparticles and their optical properties defined by plasmon excitation. The optical properties of the irradiated areas are found to depend on the laser processing parameters. Irradiation with nanosecond laser pulses may also induce color change of the glass, but at laser fluences where a permanent damage of the material is observed. The properties of the material at the processed areas are studied on the basis of generalized multiparticle Mie theory that is used to correlate the experimentally obtained optical spectra and the characteristics of the nanoparticles. The influence of the processing condition on the characteristics of the formed particles and the mechanism of their formation are discussed. This method can be used in fabrication of 3D nanoparticles systems in transparent materials that can be applied in the design of new optical components as metamaterials and in plasmonics.

Resume : In this work we report the progress on the obtaining and characterization of antireflective (AR) coatings from dielectric oxides for high power laser systems. For these purpose, thin films of tantalum, hafnium, aluminum and silicon oxides were obtained as mono / double/ triple-layers by pulsed laser deposition assisted by a radio-frequency discharge beam (RF-PLD). The samples consisting in two / three layers (SiO2 / HfO2, SiO2 / Al2O3, SiO2 / Ta2O5, HfO2 / SiO2 / HfO2) were deposited at different temperatures and in a controllable oxygen atmosphere, on quartz substrates. Atomic force microscopy, scanning electron microscopy, transmission electron microscopy, secondary ion mass spectrometry, X-ray diffraction and spectro-ellipsometry techniques were employed in order to investigate the resulting samples. Our results indicate that structures based on HfO2 and SiO2 layers have a lower roughness than the structures with Al2O3 or Ta2O5 as bottom layer. Moreover, the usage of HfO2 as bottom layer induces a nanostructured growth of the top layer. Furthermore, on the triple-layer AR coating, we observed that although the value of the refractive index “n” of the HfO2 bottom layer is a standard value for this material, the refractive index of the HfO2 top layer is much lower. This decrease is most likely due to the fact that the top layer of material may contain some voids. This work was supported by a grant from MEN-UEFISCDI, project PN-PCCA 38/2014 and 4N/2016, Nucleus Program.

Resume : Indium is a constituent of copper-indium-gallium-diselenide (CIGSe), which is an excellent absorber material for highly-efficient thin film solar cells but a rare element. A micro-concentrator solar cell design can achieve indium saving along with increased solar cell conversion efficiency. In such a solar cell architecture the CIGSe material is arranged in micrometer sized islands in contrast to the deposition of a thin layer used in standard cells. In this paper, the production of spatially arranged precursor islands consisting mainly of indium using laser-induced forward transfer (LIFT) is presented. The donor is a glass substrate (150 µm thick) coated with layers of copper (20-150 nm) and indium (200-1000 nm). The receiver is an 800 nm thick molybdenum film on glass intended as back contact for CIGSe solar cells. Islands of the donor material are successfully transferred via LIFT by employing 30-fs laser pulses with 800 nm wavelength and 60 µm focal spot diameter. The spacing between donor and receiver is fixed at 150 µm and the material transfer is performed by a single pulse for each precursor island. The transferred material is characterized by scanning electron and optical microscopy, profilometry and energy dispersive X-ray analyses. Matrices of copper-indium precursors can be transferred in a spatial arrangement adapted to the geometry of micro lens arrays needed for micro-concentrator solar cells.

Resume : The achievement of multifunctional biointerfaces with enhanced characteristics towards in vitro and in vivo response relies on the ability to control the surface chemical and physical characteristics of materials. In this work, biomimetic nano- hybrid coatings of copolymer (Co), lactoferrin (Lf) and hydroxyapatite (HA) were obtained by Matrix Assisted Pulsed Laser Evaporation (MAPLE) method. The morpholoy and chemical characteristics of the coating were evaluated by Scanning Electron Microscopy, Atomic Force Microscopy and FTIR measurements. The potential of biomimetic coatings to induce an inflammatory response was evaluated in vitro using as a model of inflammation THP-1 cells diferentiated to macrophages and stimulated with bacterial endotoxins (LPS). Fluorescent microscopy experiments revealed that THP-1 cells adhered preferentially to te hybrid Lactoferrin -hydroxyapatite coated surfaces when compared to films embedded with HA or Lf alone. In the presence of LPS, a decrease in the total number of cells was observed irrespective of surface covering. The lowest total and relative amount of the pro-inflammatory TNF-α cytokine release was detected in the case of Co-Lf-HA biomaterials. Surface functionalization with hybrid biomimetic Lf-HA proved to modulate the cellular response thus being an efficient method to improve the biological performances of bone implants. Acknowledgments: The research leading to these results has received funding from the Romanian Ministry of National Education, CNCS – UEFISCDI, under the project PN-II-PT-PCCA 239/2014, TE24/2015, programme Nucleu 4N/2016, and Romanian Academy Project 1/2016-2017 of the Institute of Biochemistry and University of Bucharest-Biology Doctoral School.

Resume : Here we report on single and two-layer AlN films deposited by pulsed laser ablation of poly-AlN target on Si substrates using pulsed KrF* (=248 nm, 25 ns) excimer laser with incidence laser fluence of 3 and 4.8 J/cm2 and laser pulse repetition frequency (LPF) of 3, 10 Hz and 40 Hz. Deposition was done in nitrogen pressure of 0.1 Pa and at substrate temperatures of 450 °C and 800 °C. The AlN structures were examined by TEM, HRTEM, GIXRD, AFM, FTIR and spectroscopic ellipsometry (SE) measurements. The results show that at 800 °C well textured h-AlN nanocrystallites with columned grains are formed, between the grains amorphous phase could be detected. At 450 °C, entirely amorphous AlN layer at LPF of 3 Hz and AlN nanocrystalline growth at LPF of 10 and 40 Hz occur. XRD patterns support this observation pointing to formation of small randomly oriented h-AlN crystallites. Growth of nanocrystallites similar to films grown at 800 °C is possible when the films are deposited on a high-temperature AlN “seed” layer, as they follow the columnar structure but with smaller sized crystallites and a weaker texturing. AFM imaging reveals increasing surface roughness with degree of crystallinity in the films. The structural changes are well correlated with the variation in the optical parameters registered by FTIR and SE. In the presentation, the growth mechanism will be interpreted considering also our previous studies, where the laser fluence and nitrogen pressure were systematically changed.

Resume : The surface characteristics of an implant largely determine its interactions with the surrounding host tissue. Physicochemical properties of a surface, such as wettability and surface topography, controls the adhesion, spreading and proliferation of cells on implants. In this regard, hydrophilic surfaces are preferred to promote cell adhesion; however, hydrophobic surfaces avoid bacteria attachment. In this work, we modified the surface topography and wettability of PTFE (polytetrafluoroethylene) using a laser surface treatment called laser surface texturing. This process was performed using three different laser wavelengths (λ = 1064 nm, 532 nm, and 235 nm). The influence of the laser processing parameters on the surface modification of PTFE was investigated by means of statistically designed experiments. Processing maps to tailor the roughness, and wettability, the main parameters affecting biological performance of implants, were also determined.

Resume : Bioactive glass nanoparticles show very interesting and promising characteristics due to the join of the osteointegration properties of bioactive glass materials with the high surface area of nanoparticles. The present study investigates the synthesis of 13-93 bioactive glass nanoparticles by laser ablation of solids in open air (LASOA). A CO2 laser (wavelength 10600 nm), that operates both in CW and pulsed mode, was used as laser source in the experiments. Solid bulks of 13-93 bioactive glass prepared by melt quench technique were used as targets to be ablated by laser in open air. The solid bulks targets and the obtained nanoparticles were characterised by means of X-ray diffraction (XRD), X-ray fluorescence (XRF), Raman spectroscopy, Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution electron microscopy (HRTEM). The produced nanoparticles are mainly 13-93 bioactive glass showing spherical shape and a diameter range from 10 to 80 nm.

Resume : Iron based core @ zinc oxide shell nanopowders has been synthesized for the first time my laser pyrolysis method, using various optimized Fe(CO)5, O2, C2H4 and (C2H5)2Zn flow ratios, in the reactive mixture. TEM, EDX, XRD, X-ray diffraction, Raman spectroscopy and magnetic properties were performed for a comprehensive characterization. Water based Fe@ZnO nanoparticles suspensions was prepared using L-Dopa and CMC-Na as stabilizing agents. Also, a comparative study regarding magnetic properties and bio-screening tests were performed between PBS based Fe@ZnO nanoparticles and PBS based Fe@polymer stabilized with the same protocol.

Resume : Femtosecond ablation of metal thin films has been of vivid interest since decades [1,2]. Microbumps and nanojets have been observed on thin metal films below the ablation threshold [3,4]. The generation of microbumps has been attributed to two different mechanisms considering a loss of film strength without melting [5] and due to melting [3,4,6]. In order to resolve this contradictory issue, stacked copper/silver layers have been investigated in this study. The mixing of copper and silver is mainly restricted to the liquid phase. Thus, a mixing in the microbumps was taken as a criterion for the involvement of molten phases. [1] W. Kautek, J. Krüger, Proceedings of SPIE 2207, 600-611 (1994). [2] J. Krüger, W. Kautek, Proceedings of SPIE 2403, 436-447 (1995). [3] A.I. Kuznetsov, C. Unger, J. Koch, B.N. Chichkov, Applied Physics A 106, 479-487 (2012). [4] D. Wortmann, J. Koch, M. Reininghaus, C. Unger, C. Hulverscheidt, D. Ivanov, B.N. Chichkov, Journal of Laser Applications 24, 042017 (2012). [5] Y.P. Meshcheryakov, N.M. Bulgakova, Applied Physics A 82, 363-368 (2006). [6] K.J. Schrider, B. Torralva, S.M. Yalisove, Applied Physics Letters 107, 124101 (2015).

Resume : The mechanism of the laser-induced periodic surface structure (LIPSS, "nano-ripples") formation is still controversially discussed in literature. Several mechanisms have been proposed, such as interference effects along with transient changes in the optical properties during laser irradiation [1], second harmonic generation in compound semiconductors [2], excitation of surface excited waves [3], or self-organization [4]. We report on the role of the irradiation area on the LIPSS formation on silicon and stainless steel. A strong correlation between beam area, the mean distance between defects [5], and the formation of high and low spatial frequency LIPSS was found. On silicon, irradiation with few pulses (N ≤ 5) generates low spatial frequency LIPSS (LSFL) only for beam radii greater than the mean separation of defects (w ≥ 50 µm). Higher pulse numbers (N > 5) produce LSFL and high-spatial frequency LIPSS (HSFL) independent of the beam size. For stainless steel, on the other hand, HSFL and LSFL are also found from the first pulse on for w ≥ 10 µm. This is attributed to the high number of intrinsic defects of stainless steel compared to silicon. [1] S. Höhm, M. Herzlieb, A. Rosenfeld, J. Krüger, J. Bonse, Applied Surface Science 374, 331-338 (2016). [2] A. Borowiec, H.K. Haugen, Applied Physics Letters 82, 4462-4464 (2003). [3] G. Miyaji, K. Miyazaki, Optics Express 16, 16265-16271 (2008). [4] J. Reif, O. Varlamova, S. Uhlig, S. Varlamov, M. Bestehorn, Applied Physics A 117, 179–184 (2014). [5] O. Armbruster, A. Naghilou, M. Kitzler, W. Kautek, Applied Surface Science 396, 1736-1740 (2017).

Resume : High intensity laser pulses can generate high densities of electrons in matter. One technologically important follow-up process is the deterministic multiphoton-electron coupling [1]. In the present work, the generation of high electron densities in a solid by high intensity femtosecond laser pulses [2-5] was investigated. The subsequent emission of hot electrons into an electrolyte and the electrochemistry of intermediates was monitored as a function of laser and electrochemical parameters. Results may lead to a new understanding of the fundamentals of fast hot electron electrochemical kinetics, intermediate species electrochemistry, nanomedicine [6], materials machining in liquid contact, and the generation of colloidal solutions [7]. References: [1] W. Kautek, J. Krüger, M. Lenzner, S. Sartania, C. Spielmann, F. Krausz, Appl. Phys. Lett. 69, 3146 (1996). [2] A.G. Krivenko, J. Krüger, W. Kautek, and V.A. Benderskii, Ber. Bunsenges. Phys. Chem. 99 (1995) 1489. [3] A.G. Krivenko, W. Kautek, J. Krüger, and V.A. Benderskii, Russian J. Electrochem. 33 (1997) 394 [4] A.G. Krivenko, V.A. Benderskii, J. Krüger, and W. Kautek, Russian J. Electrochem. 33 (1998) 1068. [5] V.A. Benderskii and A.V. Benderskii, Laser Electrochemistry of Intermediates, CRC Press 1995. [6] A. Vogel, J.Noack, G. Hüttman, G. Paltauf, Appl. Phys. B 81 (2005) 1015. [7] N. Lasemi, U. Pacher, C. Rentenberger, O. Bomati Miguel, W. Kautek, ChemPhysChem (2017) http://dx.doi.org/10.1002/cphc.201601181.

Resume : We report on the synthesis by Pulsed Laser Deposition of hydroxyapatite (HA) thin films from renewable biological (bovine and ovine bones) origin. The role of reinforcement agents (e.g., MgF2, Li3PO4, Li2O, Li2CO3 or Ti) on the morphology, structure, bonding strength and cytocompatibility of the films was investigated by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDS), X-Ray Diffraction (XRD), Fourier Transformed Infrared (FTIR) Spectroscopy, surface energy measurements, pull-out and in vitro tests (viability of human mesenchymal stem cells, hMSC). SEM investigations of the films evidenced a surface morphology consisting of particulates with mean diameters of (2‒3) µm. XRD analyses demonstrated that the synthesized structures consisted of a pure HA phase, with different degrees of crystallinity mainly influenced by the reinforcement agents. FTIR spectra showed a remarkable growth of a biomimetic HA layer after only three days of immersion in Simulated Body Fluids, which proves an excellent bioactivity of the films. EDS analyses showed a quasi-stoichiometric target-to-substrate transfer, the Ca/P ratio corresponding to a biological apatite. A hydrophilic behavior was evidenced for all synthesized structures which is known in the literature to correspond to an improved surface attachment of osteoblast cells. We stress upon that the measured bonding strength values of HA structures were superior to the ones imposed by International Standards. In vitro viability tests revealed that high concentrations of Li2O within HA thin films were very toxic for hMSC, whilst deposition of Li2CO3, Li3PO4, MgF2 or Ti promoted the cell growth on all thin film surfaces. Taking into consideration the proven characteristics, low fabrication cost from sustainable resources and the good biocompatibility, these reinforced biological-derived materials could be considered a prospective solution for future metallic implants development. Acknowledgements: LD, ACP, GPP and PEF acknowledge with thanks the support of the Romanian National Authority for Scientific Research and Innovation, CNCS-UEFISCDI, under project number PN-II-RU-TE-2014-1570 (TE 108/2015) and Nucleus programme - contract 4N/2016.

Resume : E-coli microorganisms represent a serious cause of hospital associated infections. E-coli have the capability to adapt to different environments and modify their pathogenic properties. Therefore, this work aims to design and to produce a microfluidic system able to amplify the DNA from E-coli. Micro-channels and micro-cavities have been fabricated by laser technique in different polymers for their application in 3D microfluidic systems. An UV laser was used for irradiation. The morphology, dimensional accuracy, and surface conditions of these microstructures have been investigated by optical microscopy, atomic force microscopy, and scanning electron microscopy. Also, for the DNA amplification, it is necessary to integrate heating elements as metallic and dielectric thin films. Both for the insulation and conducting purposes materials with high temperature coefficient of resistance i.e. amorphous hydrogenated silicon carbide (a-SiC:H) and Ni were deposited by laser ablation. The obtained results indicate that the laser micromachining techniques applied here represent an important technical support for the realization of low-cost microfluidic chip systems with wide-ranging applications in chemical and biological analysis and clinical diagnostics.

Resume : In this study, nanocomposite coatings based on polyaniline and magnetite (PANI-Fe3O4) were synthetized using matrix assisted pulsed laser evaporation (MAPLE) technique. All experiments were carried out in a vacuum chamber using a KrF* excimer laser source (λ=248nm, τFWHM≈25ns), maintaining the same deposition parameters. The stoichiometric transfer and the morphology of the as-deposited coatings were evaluated using Fourier transform infrared spectroscopy, scanning electron and atomic force microscopy. Furthermore, the structural properties and the hydrophilic behavior of the PANI-Fe3O4 based coatings were analyzed by X-Ray diffraction and wettability measurements. The corrosion behavior of the obtained coatings was investigated by linear and cyclic voltammetry studies. In order to evaluate the biocompatibility of the coatings, MTS and immunostaining assays were carried out. The osteoblast-like cells morphology was also examined by SEM analyses, after chemical fixation. In addition, the coatings efficiency against different microbial stains was also examined.

Resume : Mesoporous carbon (MC) is an ideal material in the field of energy storage, drug delivery or sensors due to its specific properties. The high demand of the material requires a time/cost efficiency production, ideally from environmental friendly materials. We have recently implemented a time efficient procedure to obtain mesoporous carbon via photopolymerization. It was thus demonstrated that the classical long thermopolymerization at high temperatures (12 hours at 80°C) may be replaced by 60 minutes of irradiation with an UV lamp source at room temperature through a new method, light-assisted evaporation induced self-assembly (LA-EISA). In addition, we have proved that the use of molecules capable to absorb light at specific wavelengths allows accelerating reaction kinetics. By increasing UV excimer laser (λ = 248 nm, pulse duration τ = 25 ns) doses, the polymerization can be obtained in approximately 30 minutes. In order to further accelerate the process under specific laser irradiation conditions, we propose herein the introduction of new dye molecules. Specifically, Alizarin and Alizarin Red S, were introduced in the starting solutions in order to accelerate LA-EISA process applied to environmental friendly organic compounds for the production of MC. The color change of solution from colorless to dark orange during laser irradiation and UV-VIS analyses demonstrated that we can reduce the time of polymerization to few minutes. Transmission electron microscopy studies confirmed the mesoporous aspect of material after carbonization.

Resume : Pulsed Laser Deposition (PLD) and Matrix Assisted Pulsed Laser Evaporation (MAPLE) were employed for the deposition of layered double hydroxides (LDH) thin films. Pressed pellets of Mg/Al LDH were used as targets for PLD experiments. Aqueous solutions of LDH were frozen and used as targets for MAPLE depositions. In order to tailor the wetting capabilities of the films, fatty acids as lauric or stearic acids were intercalated in the lamellar structure of the LDH powders and than the outcome composite products used as targets for PLD. Composite fatty acids-LDH powders in a mixture of water and ethanol (1:1 w/w) solutions frozen in liquid nitrogen were used as targets for MAPLE depositions. A Nd:YAG laser (1064 nm, 532 nm and 266 nm) working at a repetition rate of 10 Hz were used for the ablation of the target. The laser wavelength was 266 nm and the laser conditions and the number of pulses were the same as for PLD. The influence of the deposition parameters and fatty acids presence onto the films structural and morphological properties is presented. We have obtained hydrophobic and superhydrophobic surfaces for LDH & LDH-fatty acids films deposited by PLD and we have found that the growth mechanism depends strongly on the laser wavelength. The use of laser techniques leads to oriented films, with good adherence and controlled thickness. Contact angles with values higher than 160º were measured. We compared the wettability of these films obtained by direct deposition via laser techniques from hybrid fatty acids-LDHs targets with modified fatty acid LDHs films by anion exchange procedures using pristine Mg, Al-LDH thin films obtained by PLD at 532 nm and 1064 nm respectively.

Resume : A series of novel biodegradable coatings based on triblock copolymers Poly(lactide-co-caprolactone)-block-poly(ethylene-glycol)-block-poly(lactide-co-caprolactone) (PLCL-PEG-PLCL) was obtained by matrix-assisted pulsed laser evaporation (MAPLE) and characterized. The deposition process of the copolymer was carried out using an Nd:YAG pulsed laser, operating at different fluences (0.3?0.9 J/cm2 ) with a wavelength of 266 nm and a repetition rate of 10 Hz. It was found that for specific range of fluences the main functional groups in the MAPLE-deposited thin films determined by Fourier transform infrared spectroscopy revealed the similarity with the molecular structures of the initial material, but there were significant changes depending on the deposition parameters in morphologies revealed by Atomic Force Microscopy and Scanning Electron Microscopy. The ability to control the morphology and maintaining unaltered chemistry of the deposited material through MAPLE technique is an important step in creating functional bio-interfaces in the field of biomedical research and tissue engineering. Acknowledgments: This work was supported by Romanian National Authority for Scientific Research (CNCS?UEFISCDI), under the projects PNII- PT-PCCA-2013-4-199, PN-II-RU-TE-2014-4-2434 and Nucleus programme- contract 4N/2016.

Resume : The iron-doped LiCoPO4 (FeLCP) is an alternative cathode for high-voltage lithium-ion batteries because showed improved galvanostatic cycling performances. In this work thin films for lithium-ion microbatteries have been fabricated using ns PLD (Pulsed Laser Deposition) in the presence of a gaseous environemnt. The influence of the deposition parameters, e.g.different argon and oxygen pressures, substrate types (stainless steel and silicon) and post-annealing on the crystallinity and morphology of thin films has been investigated. The structure of the deposits has been analyzed by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Well crystallized and homogeneous thin films have been grown at ambient temperature without high substrate temperature or post-annealing treatments and it is found that the crystallinity and the structure of the thin films depends on pressure condition. FeLCP thin films have been also characterized in lithium cells for analyzing the reversibility of the lithium ion batteries. In order to clarify the mechanism of deposition leading to the morphology and composition found in the deposited films, the plasma obtained in different experimental conditions has been investigated by optical emission spectroscopy and ICCD fast imaging.

Resume : Laser pyrolysis has proven a viable and trustworthy method of TiO2 nanoparticles fabrication, ensuring good quality and wide variety of nanoparticle morphologies and sizes. In this work, phase controll is obtained by one step experimental parameter modulation during laser pyrolysis process or in combination with thermal annealing. High phase purity rutile and anatase TiO2 nanoparticles are synthesized from TiCl4 and C2H4 gas mixtures, with air as oxygen donor, under CO2 laser radiation. The nano-titania samples are analysed by X-ray Diffraction, EDS, SEM and Raman spectroscopy. Principal Component Analysis of Raman spectra is a statistical method that is able to characterize multiple samples simultaneously, giving good estimated value for TiO2 anatase nanocrystallite dimensions and dopant content. This study supplements the method applicability onto rutile TiO2 nanocrystallite dimensions, proving its wide-spread pliability towards nanoparticle discrimination and vibrational behaviour interpretation.

Resume : Porous and ordered thin carbon micro-structures tailored by processing conditions were synthesized by Matrix-Assisted Pulsed Laser Evaporation followed by subsequent thermal treatment. The procedure consists of pulsed laser irradiation of a cryogenic target composed of environmentally friendly phloroglucinol/glyoxylic acid carbon precursors dissolved in different solvents. An excimer UV KrF* laser source (λ = 248 nm, τFWHM = 25 ns) was used for targets evaporation. The material was expulsed from the target pulse by pulse and immobilized on a solid facing collector inside a stainless steel reaction chamber. By modifying processing conditions such as laser energy or target solvents we have obtained thin material coatings of hundreds of nanometers with various nanomorphology onto different facing collectors. The coating assembling was evaluated by Fourier transform infrared spectroscopy, while the different nanomorphological features of the surfaces evidenced by atomic and scanning microscopy studies. The samples were further exposed to a thermal annealing treatment for material carbonization. Different ordered carbon micro-structures exhibiting either uniform or disordered porosity were synthesized directly onto various collectors and analyzed by transmission electron microscopy. Such hybrid collector/porous carbon pair structures with controllable textures could exhibit synergistic effects with great potential for energy storage or drug delivery applications.

Resume : This study presents fabrication of ZnO nanostructures by pulsed laser deposition in air at atmospheric pressure. The laser ablation was performed by nanosecond pulses delivered by Nd:YAG laser system. Due to the high density of the surrounding media the condensation of the ablated material occurs close to the target as nanoparticles and aggregates were formed in the plasma plume. The produced nanoagregates were deposited on quartz or Si substrate where they grew in a defined nanostructure. The physical properties of the obtained structures were studied as a function of the process parameters. It was found that the morphology of the as-deposited material strongly depends on the PLD geometry. The porous structure observed in the ZnO samples suggests that they could be used in the construction of sensors devices.

Resume : Laser ablation synthesis in solution (LASiS) becomes a great alternative to traditional chemical and physical methods for obtaining metallic or oxide nanoparticles. The technique is required and strongly recommend when you want to obtain nanoparticles with very high purity and stability in the absence of stabilizing substances. In this paper we report the obtaining of nanoparticles of titanium oxide in intense optical field (≈1015 W/cm2) by femtosecond pulsed laser ablation of TiCl3 aqueous solution. During experiments we have varied more parameters including: aqueous solution concentration (2%, 4%, 6%), irradiation time (30min, 60min and 90min) and optical field intensity to correlate with the structural or morphological changes of the particles. The solution obtained after irradiation was slowly dried to remove the water; the resulted nanopowder was investigated using XRD, UV-VIS, DLS and TEM. The structural results show the presence of titania-rutile phase (JCPDS nr.00-021-1276), with mean crystallite dimensions in the 4-6 nm range. The high purity of titania-rutile nanoparticles is revealed by the perfect matching of the sample peaks and the PDF card of International Center of data diffraction (ICDD).

Resume : The research is focused on fundamental study of processes and effects of interaction of short and ultra-short laser irradiation with optical transparent nanocomposite biocompatible polymers. Laser generation from ultraviolet to near infrared regions of the spectrum is applied. The high optical transparency of the biopolymers and the requirements for precision and high quality processing demands for knowledge of the mechanisms and physical processes during interaction of laser irradiation with the material. Changes in physical and chemical properties due to laser surface modification are experimentally and theoretically studied. Various process parameters (laser wave length, pulse duration, fluence and number of pulses) are examined. The preliminary results show promising prospects of implementation of such laser-based methods for micro- or nano-fabrication of optically transparent biopolymers for interface devices in bioengineering technologies such as neural implants.

Resume : Engineering the optical properties of materials by nanostructures is an interesting field of research, which is under intense investigation with important applications in the fields of photonics and metamaterials [1]. Metallic nanostructures are especially interesting due to their ability to localize light below the diffraction limit. The strongly localized fields are useful for improving the efficiency of photovoltaic (PV) devices [2] or for optimizing optical non-linear processes. In this presentation, thin-film ablation of the phase-change material Ge2Sb2Te5 (GST) is investigated using a tunable femtosecond laser. A detailed study of both phase change and ablation and associated thresholds as a function of film thickness and excitation wavelength in the near-infrared (NIR) region is presented and compared to calculations. The application-related motivation of the study is its ability to check electrodynamic calculations of the near-field distributions in the vicinity of metallic nanostructures. This is achieved by placing the structures on top of GST and irradiating around the ablation threshold, thereby directly imprinting the local field enhancements in the GST [3, 4]. Experimental verification of these calculations is essential as they will be used for future optimization of solar cells through enhanced upconversion of NIR light [5]. [1] L. Novotny, and B. Hect. Principles of Nano-Optics, 2nd ed., Cambridge University Press (2012). [2] H. Atwater, and A. Polman, Plasmonics for improved photovoltaic devices, Nature Mater. 9, 205 (2010). [3] P. Kühler, et al., Quantitative imaging of the optical near field, Opt. Expr. 20, 22063 (2012). [4] C. David, P. Kühler, F. J García de Abajo, and J. Siegel, Near-field nanoimprinting using colloidal monolayers, Opt. Expr. 22, 8226 (2014). [5] J. C. Goldschmidt, and S. Fischer, Upconversion for Photovoltaics – a Review of Materials, Devices and Concepts for Performance Enhancement, Adv. Optical Mater. 3, 510 (2015).

Resume : Nanostructures of noble metals are produced by the method of pulsed laser ablation in liquid. Solid Au and Ag targets are immersed in double distilled water for this purpose. A CuBr laser in MOPA (Master Oscillator – Power Amplifier) system generating two wavelengths at 511and 578 nm, pulse duration of 30 ns and repetition rate up to 20kHz is employed to create different colloids. The impact of the laser pulse repetition rate and fluence variation on the morphology of the created nanostructures has been studied. Optical extinction spectra of the colloids in the UV/vis region are used for indirect assessment of the changes in the shape and size distribution of the nanostructures. Their visualization is achieved by transmission electron microscopy (TEM). Particular attention is paid to the influence of the relevant parameters in the formation of nanowire networks and control of their morphology. This morphology was modified by additional illumination of the already fabricated colloids with an appropriate laser light after the termination of the ablation process. The structure and phase composition of the nanostructures were studied by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED).

Resume : The main direction of modern material science is development of new materials and coatings with complex of high mechanical properties. High-energy laser treatment is promising direction for surface hardening of materials and increasing operating characteristics of products. Investigated regularity of structure formation and phase composition surface layers steel alloys during laser thermal processing and laser thermo-chemical treatment for increasing microhardness and wear resistance. Established appearance areas with periodic (quasieutectical) structure formed in the area of melting iron alloys under laser doping of titanium carbide TiC, due to rapid mass transfer of atoms of titanium, iron and carbon at high concentration gradients, temperature and stress. It gives opportunity of producing materials with high wear resistance Offered model ideas about peculiarities of the formation of nonequilibrium local inhomogeneous structures with dispersed interstitial atoms and properties surface layers of steel alloys after laser treatment in the reaction medium with different chemical composition and physical state. It is shown that processes on the outer surface of the micron and submicron layers, thermodynamically determine the patterns of diffusion in volume of material.

Resume : Composite thin films of conducting polymer (polyaniline (PANI) grafted Lignin) – magnetic nanoparticles (Fe3O4) embedded drug (gentamicin sulfate) were deposited by matrix assisted pulsed laser evaporation (MAPLE) technique using dimetylsulfoxide (DMSO) as a matrix solvent. The main goal of this study was to obtain the controlled release of the therapeutically active substance, under the action of a magnetic and electric fields for use of these coatings for biomedical applications. In order to find the optimal deposition parameters, we conducted a study of laser fluence (0.3 - 0.5 mJ/cm2) .The structures were studied by SEM, XRD, AFM, FTIR, UV-VIS and were submitted to biological assays. It follows that the deposited thin films exhibit a convenient nanostructured surface for bone implants and the unaltered transfer of the initial biomaterials. The obtained structures are corrosion resistant, as resulted from electrochemical measurements. Biocompatibility assay (MTT, imunostaining and cellular morphology) showed that composite coatings are not cytotoxic for bone cells, which encourages further assessment of this type of biomaterials for their application in controlled drug release at implantation sites by electrical impulse stimulation.

Resume : Laser ablation of zinc oxide (ZnO) target immersed in different liquids was used to fabricate various colloidal nanostructures. Chloroform, toluene and ethanol were used as liquid medium for the laser ablation experiments. The nanosecond Nd: YAG laser system operated at fundamental wavelengths (1064 nm) was utilized. The influence of the laser fluence on the characteristics of the produced nanostructures is studied. The optical properties of the colloids were evaluated by optical transmittance measurements in the UV–VIS spectral range. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) was employed for the evaluation of the particles size distribution and identification of the phase composition of the created nanostructures. It has been demonstrated printing of the obtained colloids on various substrates by conventional inkjet printer. The morphology of the printed area is described on the basis of SEM analysis. The presented method can be an efficient alternative of the chemical methods for producing of nanoparticles-based inks with application in organic and printed electronics.

Resume : Diamond-like carbon (DLC) have been produced by pulsed-laser deposition (PLD) of highly-oriented pyrolytic graphite (HOPG) target on transparent substrates, like quartz or glass, in order to use this DLC as a buffer layer to obtain graphene-like films on top of it by thermal annealing process performed in Ultra High Vacuum (UHV) up to 1373 K. The process of DLC production by PLD has been investigated using several techniques. Indeed the nature of the DLC (sp2/sp3 ratio, impurities incorporation, carbon rate) will depend on many parameters like fluence, laser wavelength, …. and is closely related to the plasma dynamics. Therefore the plasma dynamics have been studied by the Camille iCCD camera by Photonetics equipped with internal filter wheel using several optical filters and different time delays. The optical emission spectroscopy (OES) has been used for the spectral analysis of the plasma and the determination of the plasma parameters under different deposition (laser fluence) and acquisition (gate delay, gate width) conditions. The Andor Mechelle ME 5000 OES spectrometer equipped with iCCD camera Andor iStar has been used for this purpose.

Resume : Metallic Tin-based nanocomposites has been tested in last years as promising materials for performant anodes for Li-ion batteries. We report the single-step synthesis of novel Sn-Fe-N@Polycarbosilazane nanoparticles using laser pyrolysis technique from tetramethyltin and iron pentacarbonyl vapors introduced via ammonia carrier gas which plays also the role of sensitizer through the central injector nozzle, whereas hexamethyldisilazane HDMS molecules carried also by an ammonia flow were injected through the annular flow. The decomposition of species from the inner flow allows the formation of nanoparticles containing Sn, Sn-Fe and/or metal nitride crystalline phases covered with reticulated amorphous polycarbosilazane shells provided by co-decomposition of ammonia and organosilazane precursors from the second flow. The shell thickness was tuned using different HDMS flows and their influence on electrochemical capacity of anodes constructed using these nanocomposites in Li-ion batteries was evaluated.

Resume : In this work polydimethylsiloxane (PDMS) intraocular lenses were processed by using ultra-fast laser pulses delivered at high-repetition rate. A modelocked Ti:Sapphire laser system (Mira 900, Coherent) delivering 120 fs laser pulses at a central wavelength of 800 nm and a repetition rate of 76 MHz was used to process the samples. Laser processing parameters were modified to produce parallel tracks inside the substrate. Processing configuration was also modified to counteract the low optical absorption of the substrate at this laser wavelength. It was found that by placing the sample onto a Ti-doped cellulose substrate thermal accumulation was produced so that a significant laser damaged could be produced on the sample. Processed samples were characterized by means of Scanning Electron Microscopy SEM, Energy Dispersive X-ray Spectroscopy EDX, Attenuated Total Reflectance-Infrared Spectroscopy ATR-FTIR, and Raman Spectroscopy.

Resume : Due to their layered structures, calcium cobaltite materials (CCO) like Ca3Co4O9 for example, appear to be promising for thermoelectric (TE) application. The thermal and electrical conductivities and the thermoelectric power can be tuned by controlling the oxygen deficiency in CCO films. Smooth, dense, and homogeneous films, with different stoichiometries and crystalline state were prepared by pulsed-laser deposition (PLD) in order to modify charge carrier concentration and thermal diffusivity of material. By adjusting the oxygen partial pressure in the 10-6 to 10-1 mbar range during the PLD growth, nearly stoichiometric or highly oxygen deficient CCO films were deposited onto single crystal substrate (sapphire, (100-oriented Si) hold at various temperatures (from room temperature, up to 700°C). The electrical, thermal and thermoelectric properties were determined using an original equipment (Micro-ZT meter) specifically designed for TE measurements on thin films, and were correlated with the structural, and morphological characteristics of the thin films.

Resume : By the novel technique of in-situ nanosecond-laser micro-depassivation and potentially controlled repassivation we show the temporal change in the repassivation mechanism[1,2] of Al as a time-dependent linear combination of a high-field model of oxide growth (HFM)[3] and the point defect model (PDM)[4] within a single experiment. The observed mechanistic switch in transient repassivation current-decay occurs independently of the active electrode size and effective repassivation time at all overpotentials. It is observed, that the ratio of total passivation time to the point of model switch approaches a constant value after repetitive laser treatments, which can be attributed to a laser-induced defect-centre saturation in the heat affected and shock affected zone. For that, charge transport in the growing oxide film on aluminium induced by in situ nanosecond-laser depassivation[5,6] of plasma electrolytically oxididized (PEO) coatings was recorded in real time and evaluated according to well established theories of oxide-film formation and growth kinetics. [1] T.O. Nagy, M.J.J. Weimerskirch, U. Pacher, W. Kautek, Z. Phys. Chem. 230 (2016),1303–1327. [2] T. O. Nagy et al., Appl. Surf. Sci. 302 (2014) 184-188. [3] T.P. Hoar et al., J. Phys. Chem. Solids 9 (1959) 97-99. [4] D. D. Macdonald, J. Electrochem. Soc. 139 (1992) 3434-3449. [5] A. Cortona and W. Kautek, Phys. Chem. Chem. Phys. 3 (2001) 5283-5289. [6] W. Kautek and G. Daminelli, Electrochim. Acta 48 (2002) 3249-3255.

Resume : Lanthanum hexaboride (LaB6) and Hafnium Carbide (HfC) thin-films were grown both by ns (ArF, 193 nm) and fs (Ti: Sapphire, 800 nm) Pulsed Laser Deposition. LaB6 and HfC layers can act as efficient electron emitters for high temperature (<2000 °C) thermionic cathodes due to their low work function (around 2.3 eV and 3.3 eV, respectively). The physical properties of the ceramic thin-films deposition conditions were optimized by varying deposition temperature of the refractory metal substrate, target-substrate working distance (in the range 30-100 mm), and process atmosphere (vacuum, Ar and He pressure). Grazing incidence x-ray diffraction, scanning electron microscopy, and x-ray spectroscopy were used to investigate the properties of the deposited thin-films. Thermionic emission measurements were performed to evaluate the work functions of LaB6 and HfC layers deposited on metallic substrates.

Resume : This paper presents results obtained in high-precision ultrashort pulse laser processing of 200 µm thick molybdenum sheet metal. In the study, essential research on the ablation behavior of molybdenum as well as the influence of different processing strategies on machining results was conducted. For this, a high-PRF (pulse repetition frequency) femtosecond laser (λ = 1030 nm, τ_H = 180 fs, f_P = 1 MHz) was used in conjunction with a galvanometer scan system. By raster scanning of the laser beam across the molybdenum surface and by in-situ control of the cavity depth, local metal foils with thickness as small as 5 µm were produced. The quality of the foils was evaluated by cross section images and SEM micrographs captured from the foil surface. Finally, machining samples will be presented to demonstrate the feasibility of the high-PRF ultrashort pulse laser technology in high-precision micro fabrication.

Resume : In nature, many plant leaves have super-hydrophobic surface, such as the lotus leaf which has a micro-nano patterned surface and a wax-like component. Hydrophobic surface prevents the water to contact with the substrate easily, so that the corrosion resistance of the metal enhanced. Moreover, the super-hydrophobic surface has self-cleaning and anti-sticking properties, which is of special interest in both academic and industries field. So laser processing became the mainly strategy to fabricate the hydrophobic micro-nano patterned surface. Various complex phenomena occurs when laser irradiate to the surface of the material. The quantity of the absorbed energy on the material depends on the physical properties of the material. Laser shockwaves has commonly been used to manufacture micro-nano pattern on the surface of the material. When a laser irradiated to the polymer a shockwaves were transmitted to the inside. When both the appropriate absorption coefficient of thermoplastic polymer and the rapid pressure drop were provided, micro pattern was generated and decrease in viscosity. In this paper, we propose the novel process how to fabricate hydrophobic micro-nano pattern on the polyimide film using UV laser. Because of the polymer property for the high temperature atmosphere in laser processing, it’s difficult to creating the micro-nano scale rough pattern. So we propose the new atmosphere condition in laser process suitable for the rough hydrophobic structure. Using CO2 gas chamber for the viscosity of polymer depending on the temperature. After the creating hydrophobic pattern on the surface of the polymer, it doesn’t need to post processing like coating wax-like components, because the polymer already has hydrophobic property. It is expected to extend the wide applications in medical products and electronic products.

Resume : Zinc-doped tin oxide nanoparticles, were synthesized by the laser pyrolysis using a reactive mixture containing vapors of tetramethyl-Sn and diethyl-Zn carried by Ar, SF6 or C2H4 as sensitizer through the central nozzle and a mixture of oxygen and argon (as oxidizing agent) through the annular nozzle, all surrounded by a separate Ar flow. Here we report the successful control of crystalline mixture from both tin oxides (SnO and SnO2) by the amount of oxygen in the oxidizing mixture and the residence time in flame. TEM and XRD analysis of the synthesized nanopowders demonstrate an improved crystalline structure oriented to crystalline mono-domains when the oxygen percentage increases in the reactive mixture. Zn doping degree (up to 5 at. %) can be finely tuned by controlling Zn/Sn precursors ratio with a mean particle diameter about 12 to 15 nm as EDX and TEM analyses revealed. Spin coating technique were used to prepare thin films from samples with different Zn doping values and their optical and electrical properties were investigated.

Resume : Due to its large remnant polarization and relatively good piezoelectric properties the Na0.5Bi0.5TiO3 (NBT) and solid solution based on NBT can be considered as next generation of environmental-friendly piezoelectric materials. The solid solution Na0.5Bi0.5 TiO3- x%BaTiO3 (NBT-x%BT) exhibit a morphotropic phase boundary (MPB) for 6

Resume : Due to plasma-wall interaction mixed compositions are formed on the walls of tokamak machine, containing elements as beryllium, graphite and tungsten, including also the unavoidable intrinsic impurities as nitrogen and hydrogen. Their properties are extremely important for further cleaning procedures. To this aim in view these structures are simulated: prepared by different techniques and further characterized. Because Be is a toxic compound, in simulation experiments it is replaced by Magnesium (Mg), which has similar properties.. In our work we report on morphological and structural investigation of (C/W/Mg) thin films with various compositions deposited by pulsed laser deposition. A Nd:YAG pulsed laser at 1064 nm wavelength with the pulse width of 6 ns and a repetition rate of 10 Hz has been used to alternatively ablate C/W/Mg solid targets installed on a multitarget rotation-translation system. The layers depositions have been done in a gas mixture containing argon, nitrogen and hydrogen in different compositions, with different numbers of pulses sequences, at fluences in the range of 1.6-6.6 J/cm2and substrate temperatures of 200°, 400°, 600° C respectively. The resulted coatings were characterized in terms of morphology, optical, compositional and structural properties by atomic force microscopy (AFM), Scanning Electron Microscopy (SEM), spectro-ellipsometry (SE), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and secondary ion mass spectrometry (SIMS).

Resume : 40mol%NiO-(8mol%Y2O3)•ZrO2 thin films is selected like reference electrode because of good electrically conductivity and structural compatibility with 8YSZ electrolyte but generates undesired effects between the materials for operation in low temperature range like coarsening NiO deposited at interface. Highly oriented thin films policrystalline multilayer 40NiO-YSZ/CGO/YSZ with stable structures controlled by PLD parameters (mainly gas pressure, substrate temperature and distance target-substrate) is obtained; no reaction was detected between CGO and YSZ thin films with influence of maintaining the high electrochemical performance during the long term operation.

Resume : Laser-induced periodic surface structures (LIPSS) on metal (gold, silver, and copper) have been obtained by the irradiation of the initial surface with Ti:sapphire femtosecond laser. The morphology of treated surface has been studied with atomic force and scanning electron microscopy, and the light scattering indicatrices. The main LIPSS along with specific structures have been observed. The most probable mechanism of formation of LIPSS is associated with an interference of incident electromagnetic wave and surface plasmon polaritons (SPP) excited by the incident wave on the rough metal surface. Changing irradiation regime we try to obtain LIPSS with parameters suitable for excitation of surface plasmons by grating method. Manifestation of the field enhancement due to the resonant excitation of SPP has been obtained by surface enhanced Raman spectroscopy (SERS) of Rhodamine 6G dye on laser-induced Ag nanostructures. The gain up to 20 times has been achieved. Furthermore, the presence of dislocations and fragmentation of period of parallel strips extend spectral range of effective excitation of surface plasmons at such surfaces, in addition the presence of nanosized features increases the surface enhancement coefficient of field. Formed structures are promising for many important applications such as plasmonic emitters, biosensors, SERS, etc.

Resume : Lead-free (Ba1−xCax)(ZryTi1−y)O3 (BCZT) material has similar perovskite structure with the well-known BaTiO3, but exhibiting superior piezoelectric properties. Because is a nontoxic lead free materials the BCZT can have high applicability in biology and medicine fields. In our work we prove for the first time that BCT thin films have biocompatible properties and can be implemented in bio-medical devices. The BCTZ thin films have been obtained using pulsed laser based techniques (MAPLE and PLD). The targets for MAPLE deposition were prepared by mixing BCZT45 powders in proportions of 0.25−0.5 wt % with chloroform and successively freezing, under continuous stirring, in a solid shape in liquid nitrogen. The films growth by both methods on Pt/Si and Kapton polymer shows similar properties and high piezoelectric coefficient coupling between mechanical loading and electrical potential. The electrical potential favours the biological processes like osteogenesis. The BCTZ coatings on Kapton polymer substrates provide optimal support for osteogenic differentiation of mesenchymal stem cells. By modulating the properties of BCZT thin films, the response of cells in vitro (adhesion, proliferation, migration, electrical stimulation, and differentiation) can be adapted to the designated application. Acknowledgment: This work has been financed by the National Authority for Research and Innovation in the frame of Nucleus programme- contract 4N/2016 and the PCCA12/2014 project.

Resume : The rapid stratigraphic 3D-analysis of metal coatings on structured samples is of substantial importance in modern industrial QC/QA routine. Laser-induced breakdown spectroscopy (LIBS) is one of the most promising options to receive fast and reliable results in this field [1]. Furthermore, the knowledge of the ablation and emission properties allows for the development of custom analysis and machining approaches for layered materials. In this study various galvanic coatings of Cu and Ni at varying thickness, typically applied in industrial standard routines, were investigated. Ablation experiments were carried out using the first two harmonic wavelengths of a pulsed Nd:YAG laser and the resulting plasma spectra were analyzed using the correlation method [2,3]. For both wavelengths the absorption/ablation behavior as well as LIBS depth profiles were studied in relation to the layer thickness and compared to theoretical values [4] originating from common thermal and non-thermal ablation models. [1] Nagy, T. O.; Pacher, U.; Giesriegl, A.; Weimerskirch, M.J.J.; Kautek, W., Appl. Surf. Sci. 2016, In Press, Accepted Manuscript. [2] Mateo, M. P.; Costa, G. N.; Piñon, V.; Yañez, A., Surf. Interface Anal. 2006, 38, (5), 941-948. [3] Nagy, T. O.; Pacher, U.; Pöhl, H.; Kautek, W., Appl. Surf. Sci. 2014, 302, 189-193. [4] Matthias, E.; Reichling, M.; Siegel, J.; Kaeding, O. W.; Petzoldt, S.; Skurk, H.; Bizenberger, P.; Neske, E., Appl. Phys. A: Solids and Surfaces 1994, 58, (2), 129-136.

Resume : Among different lead-free materials available for substitution of the PZT’s family, BaTiO3 modified Na0.5Bi0.5TiO3 (NBT-BT) solid solution appears as a promising candidate on account of its good ferroelectric and piezoelectric properties. The structural, microstructural characteristics as well as piezoelectric and ferroelectric properties of epitaxial NBT-xBT thin films deposited by Pulsed Laser Deposition on different substrate (SrTiO3, SrRuO3/ SrTiO3, etc) will be presented. As a function of BT concentration, the electrical behavior can vary from relaxor to normal ferroelectric. Close to morphotropic phase boundary limit (x= 0.06), the NBT-BT thin films show a classic switching behavior and the locally measured value of effective piezoeletric coefficient d33 eff was 83 pm/V which is higher than the previously reported values for pure NBT or lead-based thin films. The NBT-BT thin films show good polarization-type switching behavior for more than 108 switching cycles. An enhanced stability of ferroelectric phase in thin films with respect to bulk has been observed and explained by their peculiar microstructure.

Resume : Using laser ablation in liquids technique, we have synthesized different type of nanostructures of BiFeO3 based materials by varying the lasers working parameters (wavelengths, laser fluences, type of liquid). Laser wavelength demonstrated to be very important as single-crystalline sheets, nanoparticles with a narrow mean-size distribution (25-28 nm) or a combination of the two have been obtained for different wavelenghts. The average nanostructures size and morphology was estimated by transmission electron microscopy (TEM) and the optical properties by spectroscopic ellipsometry (SE) and UV-Vis spectrometry (ultraviolet—visible). To evaluate their functional ferroelectric and ferromagnetic characteristics, the BFO nanostructures have been deposited as thin films by MAPLE (Matrix Assisted Pulsed Laser Evaporation).The influence of experimental parameters as solvent type, laser wavelength or thickness of the MAPLE deposited samples on the local piezoelectric response, optical, multiferoic and photocatalytic properties has been studied using XRD, HRTEM, SE, UV-VIS, PFM or dielectric/ferroelectric spectroscopy. A comparison with PLD deposited layers properties was also performed.

Resume : Laser marking has an important presence in industrial applications that range from automotive to medical and electronic components, amongst others [1], leading to constant research on materials suitable for this purpose. Metal phosphates have interesting applications in the field of laser marking. Cu2PO4OH, also named libethenite, has interesting magnetic, photocatalytic and optical properties. In addition, the controlled synthesis of libethenite can lead to interesting 2D and 3D structures for different nanotechnology applications [2]. In this work, several Cu2PO4OH were synthesized using a range of methods to investigate the effect on the absorbance and were characterized by powder XRD, FTIR, TEM and SEM. UV-VIS-NIR spectra were recorded for all samples using an integrating sphere and the absorbance was calculated with the Kubelka-Munk function from the reflectance. An additional sample was calcined at 673 K to observe differences in the optical properties with temperature. The different synthesis methods resulted in materials with very different but strong absorption intensities in the NIR region between 500-1880 nm. This strong absorption indicates the suitability of libethenite for laser marking purposes and the light green colour of the samples may lead to applications in security inks. References [1] R. Wissemborski and R. Klein, Welding and Marking of Plastics with Lasers, LTJ, 2010, 7, 19-22. [2] D. W. Kim et al., Adv. Funct. Mater., 2008, 18, 2154-2162.

Resume : Halide based perovskite materials attract an increasing scientific attention due to their outstanding optoelectronic properties, paving the way to highly efficient photovoltaic devices. In order to scale up the perovskite technology for module fabrication a precise patterning of the material layers is mandatory. In current state of the art concepts like lithography, shadow mask and mechanical scribing are applied for the patterning process. However, for high throughput industrial fabrication processes all laser-based scribing is needed to perform a fast, contactless and reliable solution. In this work the laser patterning of perovskite layers with a large range of different laser sources (ns, ps, fs long laser pulses with wavelengths of 248 nm – 2.5 µm) was investigated. Using optical and scanning electron microscopy (SEM) the morphology and topography of laser scribes as well as single laser pulse ablations were studied and compared. Both direct and indirect (rear side ablation) scribing processes are investigated and will be presented.

Resume : Organic heterostructures based on zinc phthalocyanine (ZnPc) and perylenetetracarboxylic dianhydride (PTCDA) were deposited by matrix assisted pulsed laser evaporation (MAPLE) technique on conductive flexible substrate (ITO/PET) in various configurations: layer/layer (ZnPc/PTCDA), blend (ZnPc:PTCDA) and layer/blend/layer (ZnPc/ZnPc:PTCDA/PTCDA). The effect of the heterostructure configuration on the optical and electrical properties was investigated. In the visible range of the solar spectrum, an increase of the optical absorption was observed for the prepared heterostructures regardless their configuration. The I-V characteristics recorded in dark conditions revealed higher current values for the ZnPc:PTCDA and ZnPc/ZnPc:PTCDA/PTCDA structures compared to the ZnPc/PTCDA multilayer structure. Moreover, under illumination with a solar simulator (AM1.5), a photovoltaic effect was evidenced for the all fabricated organic heterostructures.

Resume : Laser Ablation in Liquid (LAL) of metal targets for the production of ligand-free nanoparticles (NPs) has gained great interest in the last decade. The advantages of LAL are its simplicity, green synthesis and, usually, the production without additives of very stable NPs [1]. NPs can show various features as a consequence of either the laser parameters [2]or the solution used. In this work it has been surveyed the LAL of a Ti target performed in water with or without electrolytes, the effects on the generated TiO2 NPs as well as the presence of precursors of their self-assembling mechanism. The interest for TiO2 nanostructures is related to its excellent properties and possible applications in optics, electronics, biology, photovoltaic cells, photocatalysis and sensors [3]. The various forms of nanostructural titania, such as microtubes, has attracted increasing attention for its highly ordered structures and properties. In this frame, conversely from our previous research [4], the present study is focused on investigating the influence of electrolytes and laser parameters on both the production of NPs and the growth process of TiO2 microtubes. XRD spectra show that in pure deionized water the TiO2 NPs rutile phase formation is preferred. Instead, when an electrolyte is added, a different mechanism is induced so that the TiO2 NPs anatase phase is generated. In terms of photocatalytic activity, it is important to provide guidelines for the development of the metastable anatase structure since it is known to outperform the most stable rutile phase. Comparing the TEM images of the nanomaterials obtained it has been observed that a large amount of nanostructures can be assigned to nanosheets as precursors of self-assembled TiO2 microtubes. References: [1] Zeng H et al. "Nanomaterials via laser ablation/irradiation in liquid: a review" Adv. Funct. Mater. 2012, 22, 1333–53. [2] A. Nath, S.S. Laha, A. Khare Applied "Effect of focusing conditions on synthesis of titanium oxide nanoparticles via laser ablation in titanium–water interface" Surface Science 2011, 257, 3118–3122. [3] X. Chen and S. S. Mao "Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications" Chem. Rev. 2007, 107, 2891−2959. [4] A. De Bonis, A. Galasso, N. Ibris, A. Laurita, A. Santagata, R. Teghil " Rutile microtubes assembly from nanostructures obtained by ultra-short laser ablation of titanium in liquid" Applied Surface Science 2013, 268, 571–578.

Resume : The understanding and control of dynamic processes in nanoscale systems are essential in continuing the development of nanoscience and nanotechnology. As the standard silicon–based electronics reaches its size limit, molecular electronics could become a promising alternative. To turn this promise into reality, a deeper knowledge and understanding of the transient carrier dynamics inside a molecule is necessary. The aim of this research is to tackle this problem by inducing and investigating current modulations in a tunnel junctions by means of laser spectroscopy. Previous studies have suggested that optical excitation of samples in specific time intervals could provide insights into their transient carrier dynamics, paving the way for further study of nanosystems’ dynamics.1,2 Tunnelling junctions have shown excellent detecting capabilities, especially in the field of single molecule detection.3,4 Their use in the study of the transient carrier dynamics of single molecules is therefore natural. Herein we propose a novel optical control experiment which combines electrical detection in tunnelling junctions with ultrafast laser detection techniques. These junctions were fabricated by controlled electrodeposition of gold nanoparticles onto a dual electrode assembly. We believe this scheme will allow real time characterization of single molecules, such as a DNA strand, with enhanced selectivity compared to current detection techniques. The generation of excited states in the molecule will result in a modulation of the tunnelling current, from which it will be possible to study the DNA carrier dynamics. This optically–enhanced system for single molecule detection will give more insight into the molecule carrier dynamics and will aid in understanding the structure and properties of nanoscale systems. Such a system may also be used to enhance sensitivity of currently used tunnelling junctions based DNA sequencing techniques. References [1] Terada, Y. et al. Real-space imaging of transient carrier dynamics by nanoscale pump–probe microscopy. Nat. Photonics 4, 869–874 (2010). [2] Cocker, T. et al. An ultrafast terahertz scanning tunnelling microscope. Nat. Photonics 7, 620–625 (2013). [3] Ivanov, A. P. et al. DNA tunneling detector embedded in a nanopore. Nano Lett. 11, 279–285 (2011). [4] Albrecht, T. Electrochemical tunnelling sensors and their potential applications. Nat. Commun. 3, (2012).

Resume : During the last years various strategies have been adopted to enhance the performance of organic heterostructures in the optoelectronic applications. In the present study, for improving the optical and electrical properties of some organic heterostructures we used nanostructured transparent indium tin oxide (ITO) electrode. The organic heterostructures based on cooper phthalocyanine (CuPc) and fullerene C60 were deposited as multilayers or blends by Matrix Assited Pulsed Laser Evaporation (MAPLE) technique. The patterned ITO consists in two-dimensional (2D) periodic nanostructures, these being obtained by UV-Nanoimprint Lithography method. The optical and electrical properties of the organic heterostructures prepared on nanostructured ITO were compared with those presented by the same heterostructures deposited on plan ITO electrode. It was evidenced that the nanostructured transparent electrode allows the increase of the light absorption, leading to a good dissociation of the charge carriers in the investigated organic heterostructures. The prepared heterostructures are suitable in the photovoltaic applications.

Resume : The dynamics of laser produced plasma plumes is generally described by differentiable physical models1,2. Given the complexity of the phenomena involved in the laser-matter interactions, an alternative approach might be non-differentiable physical models (fractal models). In the past few years, our group proposed a fractal approach3-5 to describe the laser ablation plasma plume expansion. In the framework of our fractal hydrodynamic model, the ejected particles move on continuous but non-differentiable curves6 (fractal curves) so that all physical phenomena involved in the ablation plasma dynamics depend not only on the space-time coordinates but also on the space-time resolution scales. Additionally, the particles can be reduced to and identified with their own trajectories (geodesics), so that the ablation plasma will act similarly to a fluid lacking interactions (fractal fluid) by means of geodesics in a non-differentiable (fractal) space. We developed a more compact version of the fractal hydrodynamic model and we used it to describe the dynamics of the fractal fluid associated with a laser-produced plasma. This version of our model was obtained by using normalized variables (particle density, velocities, current density etc.) and by choosing adequate scale resolutions. The influence of external parameters on the ablation plasma dynamics is also considered by the introduction of the fractality degree as a global parameter. For the first time clear associations are proposed between fractal model variables and specific plasma parameters (electron temperature, thermal velocity, particle density). These results emphasize the practicality of the non-differential theoretical model for the study of laser–produced plasma dynamics References 1. S. I. Anisimov, B. S. Luk’yanchuk, and A. Luches, Appl. Surf. Sci. 24, 96, (1996) 2. N.M. Bulgakova, R. Stoian, A. Rosenfeld, I. V. Hertel, W. Marine, and E.E.B. Campbell, Appl. Phys. A Mater. Sci. Process. 81, 345 (2005) 3. S. Gurlui, M. Agop, , P. Nica, M. Ziskind C. Focsa, Phys Rev E, 78, 026405 (2008) 4. M. Agop, P.E. Nica, S. Gurlui, C. Focsa, V.P. Paun, and M. Colotin, Eur. Phys. J. D 56, 405 (2009) 5. P.E. Nica, M. Agop, S. Gurlui, C. Bejinariu, and C. Focsa, Jpn. J. Appl. Phys. 51, 106102 (2012) 6. I. Merches, M. Agop, Differentiability and Fractality in Dynamics of Physical Systems (World Scientific, 2016)

Resume : Two-dimensional transition metal dichalcogenides (2D-TMDs), such as MoS2 and MoSe2, have emerged as a new class of semiconducting materials with distinct optical and electrical properties. The possibility of engineering the electronic structure of atomically thin two-dimensional materials is of great importance for optoelectronic applications. In particular, alloying of 2D-TMDs can result in a wider range of band gaps compared to pure monolayers. In comparison with the standard approach used for the fabrication of 2D-TMDs and its alloy, i.e. chemical vapor deposition (CVD), which requires long processing times and high working temperatures, pulsed laser deposition (PLD) can provide a versatile approach of controlling the monolayer composition by the ratio between the deposition yield of the two materials, which is typically below one monolayer per pulse. We will exploit the growth of 2D-TMDs and its alloys by a hybrid pulsed laser deposition approach. Finally, Raman and photoluminescence (PL) spectroscopy characterization of the 2D alloys are reviewed. The band gap tuning is discussed in details based on the PL experiments and existing theoretical calculations.

Resume : The aim of this study was to develop nanostructured bioactive surfaces based on 10nm antimicrobial nanoparticles and polylactic acid with a great antimicrobial activity by limiting the attachment and biofilm formation of the Gram-positive and Gram-negative strains. Antimicrobial magnetite nanoparticles were prepared by a modified method developed by our group. Nanoparticles functionalized with eucalypt were obtained in a single step. The functionalized nanoparticles were characterized by TEM, SEM, SAED, XRD, DTA-TG and FT-IR. Thin films were fabricated by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique and further characterized by TEM, SEM, AFM and IRM. Fluence studies were realized in order to highlight the optimum deposition rate. The integrity of functional groups during MAPLE deposition was monitored by Infrared Microscopy. The samples were also characterized from biological point of view on eukaryotic and prokaryotic cells. Different cell lines highlighted the biocompatibility by qualitative and quantitative analyses, and microbiological results have demonstrated that the bioactive coatings significantly inhibited the colonization of different microbial species. The results recommend this material as an efficient approach in developing anti-infective coatings with good biocompatibility in order to be used to prevent infections in implantology.

Resume : In this study we aim to obtain a tailored thin coating based on cefepim functionalized magnetite nanoparticles (Fe3O4@CEF)/poly(lactic-co-glycolic acid) (PLGA) containing cefepim antibiotic (CEF). Matrix Assisted Pulsed Laser Evaporation Tehnique (MAPLE) was used in order to deposit bioactive thin films at different laser fluence. The prepared thin coatings were characterized by TEM, SEM, XRD, SAED, AFM and FTIR. Infrared Microscopy was used in order to highlight the best deposition rate. Biological characterization consisted in the in vitro evaluation of the thin coatings biocompatibility with respect to stem cells while their antimicrobial effect was analyzed on different bacteria strains. Biocompatibility results demonstrated that thin coatings present a good cyto-compatibility related to the stem cells, proving the ability of these non-toxic surfaces to sustain the cellular growth. Qualitative and quantitative analyses performed on microbial strains showed that the obtained surfaces exhibited an inhibitory activity against microbial attachment and colonization. Furthermore, both microscopy and viable count analyses demonstrated the ability of the thin coatings to inhibit biofilm formation of these bacteria species. All these data recommend this type of surface for prevention of microbial infections at the bone-implant interface.

Resume : The purpose of this study was to characterize and assess the impact of a novel magnetite (Fe3O4) nanosystem functionalized with the natural origin compound eugenol (E) on the Pseudomonas aeruginosa virulence, biofilm formation and QS signaling in order to advance research aimed to find alternative and personalized therapeutic approaches for severe infections produced by this opportunistic pathogen. Fe3O4 nanoparticles were obtained by a co-precipitation method and functionalized with analytical purity E. Functionalized nanoparticles (Fe3O4@E) were characterized by IR, SEM, TGA and HR TEM. One laboratory and 9 P. aeruginosa clinical isolates were utilized in the study. Growth and biofilm formation were assessed by an adapted microdilution method. Soluble virulence factors production was assessed by enzyme activity evaluation of bacteria grown on specific media. The expression of QS core genes was analyzed by qRT-PCR. Results demonstrated that the average size of the obtained nanosystem ranges 5-9nm, particles are relatively homogenous and have a low tendency to form aggregates. Subinhibitory concentrations of Fe3O4@E limited biofilms formation in a time and strain dependent manner, and significantly inhibited the production of toxin pore forming enzymes. The expression of lasI and lasR genes was three fold downregulated, while the expression of pqsR was upregulated suggesting that pqs signaling may be involved in virulence modulation after nanoparticle stimulation. The modulation of bacterial virulence and molecular signaling by functional nanoparticles utilized in subinhibitory amounts offer valuable perspectives to develop personalized antimicrobial approaches based on molecular communication control that clearly modulate pathogenicity and progression of the infectious process.

Resume : In this study we investigated the potential of MAPLE-deposited thin coatings of magnetite nanoparticles to release biologically active lysosim. Magnetite nanoparticles functionalized with lysosim were synthesized by an adapted method with diameters under 10 nm, as confirmed by XRD and TEM analyses. The deposited nanocoatings were characterized by AFM, SEM, TEM, XRD, DTA-TG and InfraRed Microscopy. The results of the microbiological analyses revealed the release of lysosim in an active form, decreasing the microbial adherence and colonization of the nano-coated surface. In vitro and in vivo assays revealed an excelent biodistribution and biocompatibility of the obtained nanosystems in tissue cultures and mouse model. Our results suggest that the obtained bioactive thin coatings present a significant potential for the design of drug delivery and antibacterial surfaces and can be used with great success in the prevention of prostheses related infections.

Resume : Femtosecond lasers are having a fundamentally different mechanism of ablation while interacting with matter. Injected energy does not contribute much to target annealing due to the very short (10-15 s) pulse duration and thus, such lasers are becoming more and more popular in various applications from material processing, nanoparticle production to elementary particles generation. The main influence of the laser beam in such a short interval is performed on the target material electrons. Due to the involved ablation mechanisms, in some particular cases in the laser-matter interaction process this interaction is also generating significant electromagnetic waves. If in most of the cases such waves might be neglected, for some particular cases (and particularly for metallic targets), the accompanying waves could become detectable and in some (very) specific conditions could even affect the functionality of the nearby devices. In this paper we present some results on the laser generated electromagnetic waves. Several metallic materials were irradiated using an 800 nm infrared beam with different energies and emitted spectra with corresponding intensities were monitored using wide-band antennas and high-frequency oscilloscopes. Some field simulation distribution for different spectral ranges were used for modeling the measured signals. Some discussions on the generation mechanisms together with the possible protection measures are also presented.

Resume : Laser-induced breakdown spectroscopy technique (LIBS) has been successfully used for the generation of chemical maps [1], although the lateral and in-depth resolutions of the technique can be further improved. In this paper single and orthogonal double pulse LIBS analysis have been compared for the generation of 2D and 3D maps in samples of different nature. Furthermore, an in-situ reconstruction of the spot generated was carried out at different pulses, following the methodology described in an earlier paper for the measurement of spatial resolution [2]. The comparison of the results here obtained suggests that the use of the double pulse LIBS approach provides a significant enhancement in the intensity of emissions lines. Consequently, a lower pulse energy can be used without sacrificing spectral quality and analytical capability which results in the improvement of both, the lateral and the in-depth resolutions of the technique when the double pulse approach is employed as compared to the use of single pulses. [1] V. Piñon, M.P. Mateo, G. Nicolas, Laser-Induced Breakdown Spectroscopy for Chemical Mapping of Materials, Appl. Spectrosc. Rev. 48 (2013) 357–383 [2] A. Casal, R. Cerrato, M.P. Mateo, G. Nicolas, 3D reconstruction and characterization of laser induced craters by in situ optical microscopy, Appl. Surf. Sci. 374 (2016) 271-277.

Resume : In this work we assess the surface modifications induced on W samples following exposure to He and He/H2 radiofrequency hollow cathode discharges. Our study addresses issues that relate to the use of W in next-generation fusion reactors, and therefore the investigation of W surface degradation following exposure and heating by plasmas to temperatures above 1000 °C is of practical importance. For these experiments we used commercially available tungsten samples having areas of 30 x 15 mm and 0.1 mm thickness. The hollow cathode plasma was produced using a radiofrequency (RF) generator (13.56 MHz) between parallel plate electrodes. The W samples were mounted as one of the electrodes. The He and He/H2 plasma discharges had a combined effect of heating and bombardment of the W surfaces. The surface modifications were studied for discharge powers between 200 and 300 W, which resulted in the heating of the samples to temperatures between 950 and 1230 °C, respectively. The samples were weighed prior and after plasma exposure, and loss of mass was noticed following plasma exposure times up to 90 minutes. Changes in surface morphology were carried out by optical microscopy, SEM and AFM. Additionally, optical emission spectra of the respective plasmas were recorded from the region localized inside the hollow cathode gap. We attempt to establish a quantitative correlation between the emission intensities of the plasma species and the extent of changes in surface morphology.

Resume : The goal of this study is the optimization of the performances of Calibration-Free Laser-induced breakdown spectroscopy (CF-LIBS) technique as a potential tool for implementing real time and in-situ analysis of steel composition. Therefore, plasma emission spectra recorded during ultraviolet laser ablation of different steel samples was compared to the spectral radiance computed for a plasma in local thermodynamic equilibrium. Using an iterative calculation algorithm, we deduce the relative elemental fractions and the plasma properties from the best agreement between measured and computed spectra. The most common approach for the investigation of elemental composition of materials by LIBS is usually performed using calibration curves, generated after measurements on standard samples with certified composition. Calibration-Free LIBS is an alternative approach for multi-elemental quantitative analysis, based on the modeling of the plasma emission spectrum. The main difficulty of steels analyses is their complicated composition, consisting of several minor and major elements. The later (e.g. Fe, Ni, Cr) exhibits very rich spectra with many intense and thus self-absorbed lines, which are not suitable for calibration-free approach. Moreover, the lack of knowledge of the Stark broadening parameters of the selected transitions for analyses and the imprecision of the spectroscopic databases may influence the accuracy of the results. Here we present the results achieved after LIBS analyses of several unknown and standard steel samples. The results were compared with complementary measurements by ICP-OES and EDX. Our study shows that laser-induced breakdown spectroscopy based on accurate plasma modeling is suitable for elemental analysis of complex materials such as steels, with an analytical performance comparable or even better than that obtained with standard techniques. *J. Hermann, (WO/2010/052380), E. Axente et al., J. Anal. At. Spectrom., 29 (2014), 553.; J. Hermann et al., Spectrochim. Acta B, 100 (2014), 189; A. De Giacomo et al., Spectrochim. Acta B, 98 (2014), 19.

Resume : The formation and nanoparticles and their incorporation dynamicss during nanosecond-laser PLD has never been well understood. Here we report the intentional formation of nearly-pure fluxes of ultrasmall (~3 nm) amorphous nanoparticles (UANPs) by gas-phase condensation in laser ablation, and demonstrate their advantages when deposited as metastable "building blocks" for the catalyst-free growth of crystalline nanostructures of different morphology and phase by the process of crystallization by particle attachment (CPA). This process is quite general, and although we concentrate on the formation of anatase, B-phase, and rutile (as well as "black anatase") TiO2 nanostructures and films, we will show the formation and integration of other oxide nanostructures (e.g. MgO, SnO2) as well as atomically-thin 2D materials (e.g. GaSe, MoSe2) by PLD of UANP precursors. Although the formation of crystalline nanostructures by dynamic particle attachment processes is well accepted in liquid-phase synthesis, such assembly processes by gas phase condensation and deposition are far less understood. Temporally- and spatially-resolved gated-ICCD imaging and ion probe measurements are employed as in situ diagnostics to understand and control the plume expansion conditions for the synthesis of nearly pure fluxes of ultrasmall amorphous TiO2 nanoparticles in background gases and their selective delivery to substrates. We describe the separation and propagation of nanoparticles from the atomic/molecular plume. These amorphous nanoparticles assemble into loose, mesoporous assemblies on substrates at room temperature but dynamically crystallize via the Ostwald-Lussac Law by sequential particle attachment at higher substrate temperatures (~400-800 oC) to grow a variety of nanostructure phases and morphologies. Molecular dynamics simulations indicate that nanoparticles arrive to the underlying nanorod to crystallize and template their crystalline orientation within nanoseconds at 600°C, then sinter between laser pulses. This work demonstrates that PLD of amorphous nanoparticles as metastable "building blocks" for attachment and crystallization is a versatile new method to explore and control the growth of thin films and nanostructures with desirable crystalline phases, nanostructure, and mesoporosity tailored for energy applications. Research sponsored by the U.S. Dept. of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Div. (synthesis science) and Scientific User Facilities Div. (characterization science).

Resume :
The ferromagnetic semiconductor EuO is amongst the most interesting compounds for spintronics devices and applications [1,2]. The high spin polarization, magnetic properties [3,4], and the possibility to integrate EuO with Si [1], GaAs [5], GaN [1] and many others technologically significant semiconductors, makes this material fascinating from basic and applied standpoints.
In this work we present a new methodology for preparing high quality textured EuO thin films in high vacuum at room temperature. The EuO textured nanocrystalline thin films are obtained by in-situ reduction from a pure Eu₂O₃ bulk ceramic target [6] by pulsed laser deposition (PLD) on Si(100) substrates, at 10^-7 mbar and without any additional gas pressure. X-ray photoelectron (XPS) spectroscopy studies prove the presence of Eu²⁺ , and the analysis of X-ray diffraction (XRD) spectra reveals only the pattern corresponding to the EuO crystalline phase with a texture along the (110) direction. The analysis of the peaks width according to the Scherrer equation points at an average crystallite size of 16 nm. Our findings indicate that PLD from Eu₂O₃ is a highly efficient method to prepare this relevant material.

[1] A. Schmehl, V. Vaithyanathan, A. Herrnberger, S. Thiel, C. Richter, M. Liberati, et al., Epitaxial integration of the highly spin-polarized ferromagnetic semiconductor EuO with silicon and GaN., Nat. Mater. 6 (2007) 882–887. doi:10.1038/nmat2012.
[2] A. Melville, T. Mairoser, A. Schmehl, D.E. Shai, E.J. Monkman, J.W. Harter, et al., Lutetium-doped EuO films grown by molecular-beam epitaxy, Appl. Phys. Lett. 100 (2012). doi:10.1063/1.4723570.
[3] B.T. Matthias, R.M. Bozorth, J.H. Van Vleck, Ferromagnetic interaction in EuO, Phys. Rev. Lett. 7 (1961) 160–161. doi:10.1103/PhysRevLett.7.160.
[4] J. Lettieri, V. Vaithyanathan, S.K. Eah, J. Stephens, V. Sih, D.D. Awschaiom, et al., Epitaxial growth and magnetic properties of EuO on (001) Si by molecular-beam epitaxy, Appl. Phys. Lett. 83 (2003) 975–977. doi:10.1063/1.1593832.
[5] A.G. Swartz, J. Ciraldo, J.J.I. Wong, Y. Li, W. Han, T. Lin, et al., Epitaxial EuO thin films on GaAs, Appl. Phys. Lett. 97 (2010). doi:10.1063/1.3490649.
[6] A. Quesada, A. del Campo, J.F. Fernández, Sintering behaviour and translucency of dense Eu₂O₃ ceramics, J. Eur. Ceram. Soc. 34 (2014) 1803–1808. doi:10.1016/j.jeurceramsoc.2013.12.034.

Resume : Cobalt ferrite (CoFe2O4) adopts an inverse spinel structure with ca. 90% of the Co2+ ions located in the octahedral sites. The strong interaction between the cobalt ions confers to the material an important anisotropy 1, which makes this material interesting in the field of spintronics, in particular as a pinning layer 2. Cobalt ferrite is the subject of renewed interest thanks to the possibility to modulate its anisotropy. One possibility to achieve this modulation is to substitute iron for a rare earth element leading to a competition between the anisotropy of the 4f element and the anisotropy of the Co2+. CoFe2O4 thin films were epitaxially grown by pulsed laser deposition on (100) MgO at 400°C in O2/N2. The cell undergoes important distortions depending on the deposition pressure. For high pressures (> 0.1 mbar), it shows tensile strain with an out of plane cell parameter smaller than bulk (8.392 Å). For lower pressures (< 0.03 mbar), the tetragonalization is stronger and reversed with out of plane and in plane cell parameters higher (8.60 Å) and smaller (8.23 Å) than bulk, respectively, yielding an interesting out of plane easy axis of magnetization. In order to fully tune the magnetization easy axis, rare-earth (RE = Nd, Gd, Tb, Dy, Er) doped thin films were elaborated. The films grow epitaxially on MgO substrates and the insertion of the RE into the spinel lattice was proved by resonant diffraction experiments performed on the CRG-BM02 beamline at the ESRF (Grenoble). 1 K. Yosida, Theory of Magnetism, Springer Science & Business Media, 1996 2 Wohlfarth E. P. (Ed.) Ferromagnetic Materials, 3, Elsevier Science Publishers B.V., 1982

Resume : Multifunctional oxide thin films from the lead-free system (K,Na) ? (Nb,Ta) ? O (KNN) are of great interest for several applications, due to their piezoelectric and ferroelectric properties. In particular, their high dielectric permittivity that can be driven by an external DC electric field enables the fabrication of tunable and miniaturized microwave devices. In this frame, KNN thin films have been grown by Pulsed Laser Deposition (KrF excimer laser) on sapphire substrates. The influence of the deposition parameters was studied in view to control the composition of the thin films and consequently the behavior of the resulting devices. Thin films were characterized by scanning electron microscopy, atomic force microscopy and X-ray diffraction before being integrated into coplanar waveguide (CPW) devices (stub resonators and transmission lines). The dielectric permittivity and dielectric loss were retrieved from microwave measurements on transmission lines whereas the tunability and the global loss were computed from the stub resonator measurements. The influence of the K/Na content on the thin films characteristics will be shown. The microwave properties will be compared to those of K0.5Ta0.5Nb0.5O3 (KTN) thin films that we have previously studied. Whereas first experiments showed a higher tunability with KTN compared to KNN, the global loss remains lower with KNN, which is a promising result for further studies.

Resume : We have grown by multi-target Pulsed Laser Deposition nanostructured YBa2Cu3O7 superconducting films with artificial pinning centres using various approaches: substrate decoration [1], quasi-multilayers [2], multilayers, targets with secondary phase nanoinclusions [3], and combinations of the above mentiones [4], involving various architectures and nanoinclusions (Ag, BaZrO3, LaNiO3,). From DC magnetization loops and AC multiharmonic susceptibility measurements we have studied the critical current densities and pinning potentials, and correlated the results with TEM images. We have found that both Jc and Up depend strongly on the types of material(s) used for the nanoengineered pinning centres and on the architectures used in the nanostructures. [1] A. Crisan, S. Fujiwara, J.C. Nie, A. Sundaresan, H. Ihara, Applied Physics Letters 79 (2001) 4547 [2] T. Haugan, P.N. Barnes, R. Wheeler, F. Meisenkothen, M. Sumption, Nature 430 (2004) 867 [3] J.L. MacManus-Driscoll, S.R. Foltyn, Q.X. Jia, H. Wang, A. Serquis, L. Civale, B. Maiorov, M.E. Hawley, M.P. Maley, D.E. Peterson, Nature Materials 3 (2004) 439 [4] P. Mikheenko, V.-S. Dang, M. M. Awang Kechik, A. Sarkar, P. Paturi, H. Huhtinen, J. S. Abell and A. Crisan, IEEE Transactions on Applied Superconductivity 21(3) (2011) 3184 Acknowledgment: Financial support from Romanian Ministry of Research through POC Project P-37_697 nr. 28/01.09.2016 is gratefully acknowledged.

Resume : TSST has developed a large area PLD system with which oxide thin film growth on 4” silicon wafers is investigated and optimized, obtaining highly crystalline heterostructures with atomically sharp interfaces. We present the results from this system on the growth of La0.67Sr0.33MnO3 (LSMO) thin films on high quality YsZ//CeO2//SrRuO3 buffer layers on 4'' silicon wafers. Film quality is investigated with X-Ray Diffraction and magnetic characterisation. Rocking curve measurements around the LSMO (002) Bragg reflection show values of ~1degree, which is comparable to the quality of films grown in <1” small scale experiments. A growth temperature dependence in the crystallinity of LSMO is shown. With the introduction of the SRO layer LSMO films show single phase crystallinity and magnetic response for temperatures as low as 250C. When this SRO layer is lacking, fully amorphous film growth is observed at higher temperatures up to 550C. We speculate that the occurrence of this LSMO high quality crystal growth at these low growth temperatures could be understood by an improved surface diffusion induced by the SRO buffer layer, where studies have shown the dependence of surface diffusion on crystal plane termination. Recent work on BiFeO3 growth show qualitatively similar behaviour, were a drastic change in growth kinetics is understood by improved growth kinetics on A-site terminated SRO.

Resume : It is well known that Pulsed Laser Deposition (PLD) is a very flexible and versatile technique allowing fast optimization of new and complex material thin films. The unique features of PLD allow for the integration of “Beyond Moore” materials in CMOS and new devices. Among these are Pb(Zr,Ti)O3, PMN-PT, BaTiO3, LiNbO3 and other materials of interest for applications in ferroelectrics. Within the scope of the PETMEM project [1] a new ground-breaking beyond CMOS computer technology will be developed that has the potential of no less than 50 to 100 times reduction of power consumption compared to current state-of-the-art. This novel Piezoelectric Transduction Memory (PETMEM) device uses a radically different switching mechanism in order to go beyond the power limits of current devices. High strain and long term stability of the piezoelectric material are key ingredients for successful commercialization of the piezoelectronic transduction memory. These properties are generally achieved in epitaxial films of PZT or PMN-PT. Integration of epitaxial piezo layers on silicon forms therefore an essential ingredient for the realization of these memory devices. Using Solmates PLD platform, wafer-level integration of epitaxial thin films on silicon is demonstrated. The robust and reliable hardware allows uniform thin film deposition up to 200 mm diameter with high process reproducibility. In this contribution the deposition of epitaxial PZT and PMN-PT thin films on silicon wafers by means of buffer layers will be presented. The piezoelectrical and piezomechanical properties in relation to their crystalline quality will be discussed. The results of this work are the first milestone in the development of the piezoelectric memory.

Resume :
The two-dimensional (2D) semiconductor transition-metal-dichalcogenides (TMDCs) family offers remarkable and unique properties including among others indirect to direct band-gap transition in monolayer crystals, which makes them ideal candidates for optoelectronic, photonic and electronic applications [1]. Atomically thin 2D materials present high sensitivity to the surrounding environment due to their large surface-to-volume ratio, and certain materials suffer severe degradation when exposed to ambient conditions [2]. In this context, encapsulation by coating with dielectrics is an adequate strategy to preserve their integrity, as well as to ensure an optimum device performance [3,4]. Encapsulation by physical vapor deposition (PVD) is in its infancy and studies on the optical emission of encapsulated 2D crystals are scarce [5,6].
In this work we explore the efficiency of pulsed laser deposition (PLD) for the encapsulation of exfoliated WSe₂ monolayers with amorphous Al₂O₃ thin films by analyzing the composition, strain state and optical response of the encapsulated monolayers. Our results demonstrate a conformal monolayers encapsulation with no need of particular surface functionalization or pre-treatment, as required when e.g. chemical vapour deposition techniques are employed [7]. The integrity of the monolayers and strain level upon encapsulation is studied by means of x-ray photoelectron spectroscopy and Raman spectroscopy. The optical response of the encapsulated monolayers has been assessed by micro-photoluminescence studies at 10 K. Our findings indicate PLD as a promising technique for the encapsulation of 2D materials. Advantages and disadvantages with respect to other techniques will be discussed.

1. Kobolov, K. S. & Tominaga, J. Two-Dimensional Transition Metal Dichalcogenides. (Springer Series in Materials Science, 2016).
2. Kim, J.-S. et al. Toward air-stable multilayer phosphorene thin-films and transistors. Sci. Rep.5, 8989 (2015).
3. Wood, J. D. et al. Effective passivation of exfoliated black phosphorus transistors against ambient degradation. Nano Lett.14, 6964–6970 (2014).
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Resume : Films of chalcogenides are becoming increasingly important because of their role as absorbers in thin-film solar cells. These absorbers are typically sulfides, selenides or tellurides, of which CIGS (Cu(Ga,In)Se2) and CdTe have been studied comprehensively during the last thirty years. A new, promising, but less studied material is CZTS (Cu2ZnSnS4) which recently has reached a solar cell efficiency slightly below 10 %. We have been inspired to produce films of quarternary sulfides by the success of pulsed laser deposition (PLD) for fabricating high-quality (stoichiometric) films of high-temperature superconductors for more than two decades. However, films of CZTS have turned out to be difficult to produce by PLD, not only because the films should have a surplus of Zn relative to Cu to make good solar cells, but also because the mass transfer from target to films is incongruent in contrast to expectations of PLD as a stoichiometric film growth process. Films of CZTS and CTS (Cu2SnS3) have been produced by PLD at a fluence from 0.2 J/cm2 to 2 J/cm2 on room-temperature substrates with nanosecond lasers with wavelengths of 248 nm or 355 nm in vacuum. The resulting film composition was deficient in copper at low fluence and in sulfur in general for both chalcogenides. The most surprising feature was a strong decrease in the copper content of the films with decreasing fluence. The results will be discussed on the basis of the thermodynamic properties of the materials.

Resume : The pulsed laser deposition (PLD) is a versatile technique to grow high quality thin films in the laboratory to investigate the role of structure and composition on various properties. Changes of the deposition conditions (substrate temperature, nature and pressure of the gaseous atmosphere, laser fluence, repetition rate, laser wavelength and deposition geometry), which are simple to implement, will result in the growth from a single target of films having a wide range of compositions, structures and properties. The main disadvantage of the technique is the non-uniform thickness profile of the deposited films, which is readily observed, especially for transparent films that show thickness interference fringes. However, there are lateral non-uniform compositions and structures as well, which could result in different properties. We investigated lateral non-uniformity of PLD grown films structure and composition using X-ray symmetrical and grazing incidence diffraction, X-ray reflectivity, X-ray diffuse scattering, nanoindentation, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis and Rutherford backscattering spectrometry techniques. Several transition metal nitrides and carbides such as ZrC, TiC, ZrN, TiN as well as indium zinc oxide and indium gallium zinc oxide films were investigated as typical examples of compounds containing atoms with different atomic masses.

Resume : In this paper, we present our work on silicon-germanium (SiGe) nanoparticles grown by Pulsed Laser Deposition (PLD). Semiconductor nanoparticles have many interest in the microelectronic domain as well as optical converter for photovoltaic applications. The PLD appears to be an advantageous technique to obtain stoichiometric and size controlled nanoparticles. By ablating high purity targets of each material, and by measuring the relative thickness of the deposited material, both deposition rates are extracted at various fluences. To insure SiGe stoichiometric and homogenous films, silicon and germanium pure targets are ablated alternatively at a deposition rate much lower than one monolayer per pulse. The silicon and germanium relative ratio is measured by Rutherford Backscattering Spectroscopy (RBS). Size and density are controlled by perform the deposition at various temperatures and measured by Atomic force microscopy (AFM). Indeed, heat brings enough kinetic energy to the atom clusters to allow coalescence on the substrate surface. Nanoparticles crystallinity is confirmed by Raman spectroscopy. It is observed that, at higher substrate temperature, the nanoparticles size is decreasing in correlation to an increase of the density. Photoluminescence experiments are performed on the deposited layers. Actual results don?t show any photoluminescence behaviour, probably due to a very high particles density. Forthcoming experiences are in progress to improve that point.

Resume : SmCo is a permanent magnetic material having peculiar characteristics. It can be used in different application field like electronic, environmental control and medicine. SmCo nanoparticles could be used in hyperthermia treatment in oncology . Hyperthermia is the procedure that increases the local temperature of tumor tissue to 40°- 43° C. In this range of temperature, the number of cancer cells could be reduced. SmCo nanoparticles properties will be measured by using structural and magneto-optics facilities. The proposed analysis could help in using the SmCo nanoparticles in the hyperthermia field.

Resume : Nowadays, there is an interest in using two-dimensionally (2D) organized materials as inorganic layered double hydroxides (LDHs) materials, to produce photofunctional organic-inorganic thin films. Here we present intercalation of organic chromophores guest in layered double hydroxide host and fabrication of hybrid organic-inorganic thin film deposition using pulsed laser deposition (PLD) technique. Because of their capacity to intercalate organic anions into the interlayer space due to their high anionic exchange ability, LDHs materials, such as Mg/Al-LDHs are used as host materials for chromophore modified LDH structures. The Mg/Al-LDH powder was prepared using co-precipitation method. Commercial dye coumarin-343 was used as organic chromophore. Prepared organic chromophore modified LDH powders has been characterized by powder X-ray diffraction (XRD), FT-IR spectroscopy, elemental analysis and differential thermal analysis (TG-DTA) shows that the coumarin-343 has been successfully intercalated into LDH. Coumarin modified Mg/Al-LDHs thin films were deposited using a Nd:YAG laser working at 532 nm and 10 Hz repetition rate. The gracing incidence - X-Ray Diffraction (GI-XRD) and photoluminescence measurements were used for the thin film characterization. The results show that these organic-inorganic hybrid thin films obtained via pulsed laser deposition (PLD) can be used in optical devices.

Resume : Defining solar cell segments and connecting those in series is a viable approach to reduce ohmic soles and adapt the output voltage in large area thin film solar modules. Here we focus on two promising thin film photovoltaic technologies based on Cu(In,Ga)Se2 and organometallic halide based perovskite absorbers. Laser scribing of thin films is one key technology to increase the efficiency of PV modules and to enable a high speed and precise patterning process. However laser scribing of thin films is facing different challenges that must be solved. Some of these challenges are: selective ablation of single layers and layer stacks, low damage of the material outside and below the scribing line, and reduction of contaminations during ablation processes. Here we present thin film photovoltaic devices scribing processes with different laser sources (UV to IR and ns to fs pulse length). Further the mechanism of laser scribing is discussed together with the results and applications to photovoltaic module fabrication.

Resume : Sapphire is commonly used in solar cells because of its thermal properties, cost and ability to make in large areas. Unfortunately, it is an extremely hard material and one that is difficult and time consuming to etch using lithography and wet etching. Laser micromachining is a versatile method ideally suited for prototyping components of solar cells using the layer-by-layer removal of material to create the desired features. We created prototype sapphire wafers with channels etched for circulating water for cooling and filled with conductive ink. We have modeled and demonstrated a method for laser etching sapphire using a low fluence (120 mJ/cm2) ArF 193 nm excimer laser and custom software to control motorized stage components. Depending on the desired depth and shape of the feature micromachining can take several hundred passes, eventually achieving depths up to 300 um. Aspect ratios (depth to width) of 5:1 were achieved in 300 um deep sample channels. Test channels to fill with conductive inks were machined to dimensions of 200 um wide by 300 um deep. The impact of firing frequency and beam shape on the rate of ablation was investigated as well, varying from 50-250 hz and using beam shutters and motorized iris. The results are consistent and the model allows one to easily generate laser tool paths. The physical model is incorporated into a custom software control suite that automatically translates a specified geometric design into a machine tool path.

Resume : We present an up to six-fold enhancement of the ultra-violet emission of ZnO using an Al thin interlayer film between the Si substrate and ZnO thin film, and a post-fabrication laser annealing process. The laser annealing is a cold process that preserves the chemical state and integrity of the underlying aluminum layer, while it is essential for the improvement of the ZnO performance as a light emitter and leads to enhanced emission in the visible and in the ultraviolet spectral ranges. In all cases, the metal interlayer enhances the intensity of the emitted light, either through coupling of the surface plasmon that is excited at the Al/ZnO interface, in the case of light-emitting ZnO in the ultraviolet region, or by the increased back reflection from the Al layer, in the case of the visible emission. In order to evaluate the process and develop a solid understanding of the relevant physical phenomena, we investigated the effects of various metals as interlayers, the metal interlayer thickness, and the incorporation of a dielectric spacer layer between Al and ZnO. Based on these experiments, Al emerged as the undisputable best choice of metal interlayer, because of its compatibility with the laser annealing process, as well as due to its high optical reflectivity at 380 and 248 nm, which leads to the effective coupling with surface plasmons at the Al/ZnO interfaces at 380 nm, and the secondary annealing of ZnO by the back-reflected 248 nm laser beam.

Resume : The generation of a photonic nanojet in the vicinity of a dielectric bead is a known and documented phenomenon. This propagative, slightly diverging, light beam does not obey to the usual laws of optical geometry. For instance, the Full Width at Half Maximum can be smaller than the wavelength, thus going beyond the diffraction limit. These useful properties make the photonic nanojet an excellent way to perform subwavelength micromachining. The shaping of optical fibre for nanojet generation is commonly done by thermoforming. However, this method has some drawbacks: the curvature of the tip is hard to control and the effect on the size of the core and its concentration in dopant is unknown. Several research teams have investigated the shaping of optical fibres by means of chemical etching. This study focuses on a two steps fabrication process to obtain the desired tip shape. The optimisation of the shape was made by 2D modelisation, by finite elements method, of the photonic jet out of the fibre. The fused silica fibres were first thermoformed to obtain the required tip shape, and then isotropically etched in HF. The characterisation of the fibres was carried out by the direct ablation of silica and photosensitive resin insulation. The results were studied by white light scanning interferometry. The encouraging results prove that the combination of thermoforming and chemical etching can lead to highly accurate fibre tip shaping for Photonic NanoJet Material Laser Processing.

Resume : In this study, we demonstrate that nonlinear optical microscopy is a promising technique to characterize organic printed electronics. Using ultrashort laser pulses we stimulate two-photon absorption in a roll coated polymer semiconductor and map the resulting two-photon induced photoluminescence (TPPL) and second harmonic response. First, we show that the different nonlinear optical signals can be used to discriminate between the polymer semiconductor material and embedded nanoparticles which constitute the electrode in a real device. Next we demonstrate that the TPPL quenches when applying a current between source and drain; this decrease can be used to determine the electrical characteristic of the device. Finally, we show that the TPPL increases with higher temperature in the 20 - 120 °C range, closely following the supported current characteristics of the semiconductor. We propose that the TPPL is a good indicator to map and monitor the charge carrier density and the molecular packing of the printed polymer material. Importantly, simple calculations based on the signal levels, suggest that this technique can be extended to the real time mapping of the polymer semiconductor film, even during the printing process, in which the high printing speed poses the need for equally high acquisition rates.

Resume : The development of novel functional materials typically requires the effective fabrication of devices with specific architectures at the micro and nanometer scale. Polymer nanogratings are attractive structures that may produce functional surfaces with different properties. Well-defined gratings on polymer thin films can be fabricated by using different techniques. Standard lithographic procedures typically imply multiple-step procedures involving clean-room facilities, high vacuum or complex mask fabrication. The search for alternative lithographic methods, avoiding these demanding conditions, is attracting increasing interest in recent years. Laser techniques, and in particular the generation of Laser Induced Periodic Surface Structures (LIPSS) can be considered as a potential alternative avoiding the need for sophisticated facilities. LIPSS can develop on the polymer surface upon repetitive irradiation with a linearly polarized laser beam within a narrow fluence range below the ablation threshold. In this presentation some functionalities of polymer films with LIPSS including ferroelectricity for non-volatile memories, substrates for selective cell culture, surface enhanced Raman scattering sensors, electrical conductivity and mechanical adhesion will be discussed. In addition, some results concerning LIPSS formation in thin films of fullerene derivatives will be presented and put into perspective of LIPSS in polymer materials.

Resume : Considering that laser-induced surface modification in the form of LIPSS (ripples) results in a modification of surface properties like wettability, we generated extended LIPSS areas (2*2 mm²) on stainless steel and silicon (100) targets. We used multiple pulses from a Ti:Sapphire laser (800 nm / 100 fs / 1 kHz) at a fluence in the range of 0.3 - 2.0 J/cm² on a spot of 7.85*10 -5 cm² and scanned the target under the spot to cover a large area. Subsequently, we tested the wettability of both surfaces in comparison. In our experiments, we systematically changed the irradiation dose by varying the scanning speed and thus dwelling time per spot. The resulting surface modifications changed from very regular linear structures with a lateral period of about 500 – 600 nm to complex patterns of 3-D microstructures with several-nm feature size, hierarchically covered by nano-ripples. We optimized the irradiation parameters, to obtain structured macro-surfaces with different morphological features: homogeneously structured areas with micro-/nanopatterns and areas exhibiting patterned regions with LIPSS of different lateral periods. We investigate the morphology difference between the two targets and their impact on wettability.

Resume : Diffractive elements manufacturing is of great interest in the fields of optics and ophthalmology. In this work fabrication of linear periodic patterns in polydimethylsiloxane (PDMS) intraocular lenses by means of the Direct Laser Interference Patterning DLIP technique is studied. As laser source, a Q-Switch Nd:YAG laser (Quantel Brilliant) coupled to second and third harmonic modules emitting linearly polarized 4 ns pulses at 355 nm with 20 Hz repetition rate was used. Laser processing parameters in terms of exposition time were modified to produce the linear patterns. Processed samples were characterized by means of optical confocal microscopy, Scanning Electron Microscopy SEM, Energy Dispersive X-ray Spectroscopy EDX, Attenuated Total Reflectance-Infrared Spectroscopy ATR-FTIR, and Raman Spectroscopy.

Resume : The arrangement of nanometer sized voids, induced by focusing intense laser radiation within transparent material allowed the generation of transparent components with dimensions in the micrometer to nanometer range due to internal contour cut and thus satisfy the progressive miniaturization of products in micro optics and medical technology. For further improvements in the precision of those components a deep understanding of the involved processes during the interaction of laser radiation within the material are necessary. In this work, voids inside bulk polylactide (PLA), a bioabsorbable polymer, were generated using femtosecond laser radiation (λ = 1030 nm, τ_H = 180 fs) with single and multiple pulses. For the experiments the pulse energy and position of the focal plane into the material was variated and the dependence of the spot size was examined. By the use of four microscope objectives (f = 12.5, 10, 4 and 2 mm) focus radii of 5, 3.3, 2 and 1.2 µm were achieved, respectively. The dimensions of the voids were experimentally determined as a function of the intensity. Differences in the lateral and axial extent of the voids were obtained for different defocusing depths and focus radii at same intensities. Furthermore, the intensity distribution of the laser radiation inside the material for the different focus radii and positions within the material and their dependence on the lateral and axial size of the voids were simulated and compared with the experimental results.

Resume : Antimicrobial resistance has been recently identified by the World Health Organisation as a global threat and the need for novel diagnostic tools has been stressed. Current routine empirical antibiotic therapy protocol involves laboratory based bacterial culture testing which can take up to 2-3 days. However, if the specific microbe species causing an infection can be quickly identified earlier on, it will allow doctors to prescribe a specific targeted antimicrobial instead of using a broad spectrum antimicrobial. In this work, we will present our preliminary results on the use of a laser-based fabrication technique of paper-based diagnostic tests via photo-polymerisation. The technique allows the creation of hydrophobic barriers through the whole thickness of the paper, and therefore the creation of fluidic channels and test zones in many different shapes, sizes and patterns. The laser-based direct-write procedure is non-contact, non-lithographic and mask-less and uses a low-power 405nm diode laser. The laser-structured paper can then be infused with chromogenic agars that allow the growth and detection of different bacteria. These devices are analogues of the commonly available agar plates and will allow the timely detection of multiple pathogens at the point-of-care. These paper-based diagnostic sensors fabricated via our laser-based technology are cheap, easy-to-use and allow rapid testing of either pathogens or their antimicrobial resistance to antibiotics.

Resume : The ability of processing through laser beams different kinds of metallic powders for production of 3D components with complex geometries has been gaining an impressive and growing attention for specific industrial applications. The process which can be distinguished as Selective Laser Sintering or Selective Laser Melting is even considered, more generally, as Additive Manufacturing where layer by layer material is built by the interaction between a laser beam and a powder bed. The rapid heating of the powder due to the laser energy transfer process followed by a rapid cooling rate induces within the manufactured material a cellular structure with fine sub-grains, which are in the range of few hundreds of micrometers. These metastable structures, which are smaller than the grain size in conventionally manufactured 316L stainless steel components, can undertake towards a recrystallization process due to either heat or mechanical treatments. In the work here presented we point out which are the microstructural features of stainless steel 316L components realized by Additive Manufacturing. Furthermore, the occurrence of a microstructural evolution is presented after experiencing to fatigue of 80000 cycles some door joints obtained by this technique. A decrease of dislocation's number, an increase of twinning due to the growth of grains and to the release of local stresses can be hypothesized following that an important role could be played by the presence of dislocations in cell boundaries as well as oxides nanoinclusion. From these outcomes it is going to be presented how the 3D components, produced by additive manufacturing, could change their features during life cycles which behavior should be taken carefully into account for their uses.

Resume : Whereas different strategies have been successfully implemented for mass production of 2D/2.5D micro and nanostructures, fabrication of 3D micro and nanostructures is usually not trivial and required time-consuming multi-step processes. In this context, Two-photon stereolithography (TPS), also called 3D Direct Laser writing (3D-DLW), is a microfabrication technique with growing interest as it renders possible the design and direct fabrication of 3D microstructures based on a photopolymerizable material. TPS can be considered as an extension of 3D printers at the micro and nanoscale levels, enabling the perfect replication of 3D objects at a miniaturized scale. Owing to the specific interaction between laser and matter (high fluence & very confined volume ~ 1 µm3), one of the current challenges is to apply the technique to the direct creation of advanced functional materials. Here, for the first time, we describe the application of TPS to the synthesis of novel complex architectural microstructures based on molecular imprinting polymers (MIPS). The latters are synthetic biomimetic receptors which have been shown to be a potential alternative to biomolecules as recognition element. First, we demonstrate the possibility to obtain active MIP microstructures by TPS from specifically optimized precursors. Then, we show examples of 3D MIP microstructures to illustrate the potential of TPS. Finally, a MIP microcantilever is built by TPS and we show the possibility to use it as a label-free microgravimetric chemical sensor.

Resume : We report what we believe to be the first evidence of direct micro peaks machining by a photonic jet (PJ). PJ is a high concentrated propagating beam with a full width at half maximum (FWHM) smaller than the diffraction limit. In our case, PJs are generated with a shaped optical fiber tip using a nanosecond laser source. Peaks with a FWHM of around 1 µm and a height of 350 nm on average, until a maximum of 593 nm, an apex of 14 nm, were repeatability achieved on a silicon wafer. The topographic characteristics were measured by a white light interferometer and an atomic force microscope (AFM). The experiments have been carried out in ambient air with a 100/140 multimode silica fiber and with a 35 kHz pulsed laser emitting 100 ns pulses at 1064 nm. We show that the phenomenon occurs only at low energies near to the ablation threshold. The material volume appears only moved to achieve the peaks. Our hypothesis would be that the matter has been melt and not vaporized; convection, heat-capillary action and momentum may be the causes.

Resume : In the present paper, laser shock peening of 0.4% C steel has been conducted by irradiating the surface with a femtosecond (fs) (Tangerine Fiber laser produced by amplitude system) laser (wavelength = 775 nm) with approximately 300 fs pulse width. The main process variables during the experiment were laser energy density, number of pulses and lasing medium. A 10% overlapping between the successive pulses was applied to ensure complete coverage of the surface. In the microstructure, there are presence of partially glassy phase, martensite and ferrito-pearlitic phases, the mass fraction of individual phase was however, found to vary with process parameters. Due to laser processing, there is introduction of residual stress on the surface which varies from vary high tensile 175 MPa to compressive -330 MPa as compare to 152 MPa of as received substrate. Laser processing under optimum process parameter improves the corrosion resistance in terms of decrease in corrosion rate as compared to as received substrate. The mechanism of corrosion resistance improvement has been investigated.

Resume : This study is related to development of laser techniques for creation of advanced Au and Ag nanostructures on SiO2 (001) substrate, which are applied to high resolution analyses – surface enhanced Raman scattering (SERS) analyses. Optical and morphological properties of the nanostructures are compared to those of the PLD deposited thin films. The fabricated structures are covered with small quantities (usually applied in agriculture) pesticides - BI 58 (dimethoate) and DDT (dichlorodiphenyl-trichloroethane), insecticide Aktara 25 BG (thiamethoxam) and Nurelle D (chlorepyriphos + cipermethrin) and fungicide Dithane DG (mancozeb - dithiocarbamate) for testing of their activity as substrates for Surface Enhanced Raman Spectroscopy (SERS). The study is directly forwarded to human health and quality of the food - check of small amounts or residue of no desired pollutants.

Resume : We report a new approach for iron based nanoparticles synthesized by laser pyrolysis when ammonia were used as gaseous sensitizer. The main goal of the present study is the synthesis by laser pyrolysis of novel FeNx magnetic nanoparticles using Fe(CO)5 and NH3 as gas/vapor phase precursors. At increased ammonia percents in the reactive mixture, the Fe3N phase (mean crystallite sizes about 11 nm) prevails over the other crystallographic phases: Fe4N. The structure of the as synthesized nanoparticles was characterized by Transmission Electron Microscopy, X-ray diffraction, Raman and Infrared spectroscopy. Magnetic measurements revealed a superparamagnetic feature at room temperature and a high saturation magnetization: up to 70 emu/g. Stabilized PBS based nanofluids with around 100-150 nm mean aggregate dimension were prepared from the as synthesized FeNx nanoparticles using sodium carboxymethylcellulose and PEG methacrylate stabilizers. Both CMC-Na and PEG coated FeNx based nanofluids exhibit a good biocompatibility. The in vitro screening tests revealed the IC50 values of the nanoaggregates and their effects on cell metabolic activity, membrane integrity and their internalization in human lung fibroblasts (MRC-5) and colorectal cancer (Caco2) cells.

Resume : The layer by layer build-up process of 3D printing is a new and promising method for the production of components in engineering. Especially the high geometric and constructive freedom, so the creation of complex geometries and integrated functional properties, such as curved cooling channels in drills is of big interest. To bring additive manufacturing to the next stage from prototype production to serial production, materials researcher evaluate various properties e.g. microstructural defects that can significantly degrade the usage properties of components, the dimensional accuracy and the surface quality. In this study we will show the suitability of microscopic methods for evaluating the quality additively manufactured indexable insert drills with curved cooling channels. Since the occurring microstructure of the components depend particularly on the powder characteristics, light and electron microscopy were in a first step utilized to observe the particle size distribution and morphology of the used steel powder. CT measurements then revealed the inner structure of the indexable insert drills and allowed a verification of dimensions from the CAD drawing. Finally light microscopy was able to check process condition dependencies. The results showed a clear microstructural evolution in response to the linear energy density (LED). Porosity and pore size decreased with increasing linear energy density (LED).