ringtolemtingdag.gq/4399.php The effect of the laser fluence on the size and shape of the synthesized nanoparticles was investigated. The experiments reveal that the production of nanoparticles is significantly enhanced in the presence of the ultrasound field. This latter technique confirms the formation of nanometric size particles, according to the observation of the characteristic surface plasmon resonances of silver at nm and gold at nm, with the SPR bandwidth being dependent on the preparation conditions.
Flocculation of metal nanoparticles is observed after a few days. In this work we address a detailed research on a novel bioactive polymeric platform, achieving long-term antibacterial and cellular proliferative properties, based on metal-organic nanocomposites that represent a breakthrough towards the ideal implant materials. We focus on material development and characterization including both in-vitro and in-vivo analysis for a novel left ventricular assist device for the treatment of chronic heart failure. Instead of standard chemical fabrication, nanoparticles are synthesized by pulsed laser ablation in liquids resulting in precursor-, contamination- and stabilizer-free complex inorganic-organic nanocomposites.
We report on physical characteristics and give deep insights into the biophysical interactions allowing long-term resistance against microbes and promoting cellular proliferation. It has been proved that processing these thermoplastic polyurethane based materials by industrial injection molding results in a prefect homogenous embedding whereas the nanoparticle stability is preserved even in the melted state due to process-related charged particles that hinders inter-particular agglomeration.
A dynamic microbial proliferation assay revealed strong antibacterial efficacy against the bacteria strains s. Finally, a 7 days long in-vivo study on hairless, immunocompetent mouse models with subcutaneous implantation showed pronounced antibacterial behavior compared to the reference material. 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 . 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  or electrochemical properties .
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. 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: 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.
Subsequent pulses rapidly within a couple of minutes improve the crystalline quality of nanocrystalline metal oxides thin films through pulsed photothermal effect. This photoinitiated nanofabrication technology opens a promising way for the low-cost and high-throughput manufacturing of nanostructured metal oxides thin films. Photonic curing of aromatic thiol-ene click dielectric capacitors via inkjet printing. A, 2,  B. Click-in ferroelectric nanoparticles for dielectric energy storage.
Interfaces, 7,  S. Instantaneous photoinitiated synthesis and rapid pulsed photothermal treatment of three-dimensional nanostructured TiO2 thin films through pulsed light irradiation. 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, 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 K.
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 and nm and at various laser fluences. Thus, an exhaustive description of the physicochemical properties of the DLC layers is a fundamental step in the research of comparable performance to ITO.
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. 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 reliable hardware is flexible for fast process optimization and allows uniform thin film deposition up to 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.
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. The experiments were performed in similar conditions of laser fluence 8.
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.
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. Following our work on the repassivation mechanism[1,2] as a time-dependent linear combination of a high-field model of oxide growth HFM  and the point defect model PDM  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. Solids 9 Acta 48 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. 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. Nanoparticles NPs formed within an ablation plume produced by the impact of a nanosecond laser pulse on the surface of an aluminum target have been directly measured using small-angle x-ray scattering SAXS .
The results for an increasing oxygen content reveal remarkable effects on the morphology of the generated particles, which include a decrease in the particle volume but a marked increase in its surface ruggedness. Molecular dynamics simulations using a reactive potential and performed under similar conditions as the experiment reproduce the experimental trends and show in detail how the shape and surface structure of the NPs evolve with increasing oxygen content .
Ex-situ analyses using local observation such MET and Raman spectroscopy but also nuclear reaction analysis NRA for elementary quantification of nitrogen and oxygen and PIXE for metallic atom analysis in the NPs, have been performed to correlate the chemical oxynitridation with previous observations and simulations. These analyses have revealed the role of the nitrogen-oxygen ratios in the gas mixture on the formation of the aluminum, aluminum nitride and oxynitride ratios in the NPs.
Moreover comparison of these treatments with those performed in air, reveals that argon also modifies the compounds formed. The key role played by chemical reactivity together with the thermodynamic conditions on the morphology of the particles thus produced shall be explored in the discussion. 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. 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. 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. C , G. 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: 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 fs duration pulses at 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. 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: The insights into the mechanisms of the NP formation may help in designing approaches aimed at minimizing the fraction of large NPs. Formation mechanisms of the laser-induced periodic surface structures LIPSS are controversially discussed since their first observation in 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: 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.
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 nm and a pulse length of 1. This setup is used to produce an intensity grating on a gold surface with a sinusoidal shape and a period of 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. 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 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. We propose a method for analyzing the elemental composition of isolated nanoparticles. 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.
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. 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.
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. Share your thoughts with other customers. For identifying the ideal combination of parameters for mimicking bug-like structures, the surfaces were inspected by optical and scanning electron microscopy. Some plasma parameters were found to be dependent on the target physical properties. In the presence of LPS, a decrease in the total number of cells was observed irrespective of surface covering.
Bulk hybrid materials HM? Partial HM's crystallization led to the increase of PL intensities in 1. 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 nm, pulse duration from to fs, frequency repetition from 1 to 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 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.
The same effect is also achieved by variation of heat treatment conditions. In the present research, different composed bismuth-germanium oxide glasses doped with chromium were treated by a femtosecond Pharos SP laser wavelength nm, pulse duration from to fs, frequency repetition from 1 to 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 and Femtosecond fs laser processing of glass is widely studied for various applications, including the fabrication of photonic devices. 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. A clear change of the glass color has been obtained when adequately illuminated i. 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.
Gandhi, Eric Mazur, and S. Sundaram, Advances in Optics and Photonics 7, Until the end of the s many wooden artworks underwent surface treatment by liquid preservatives, e. 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 fs laser pulses at nm wavelength a line-wise meandering movement of the object under the focused beam was performed. Before laser application, a chlorine measurement was done by X-ray fluorescence analysis XRF as reference. For the application of fs laser pulses on waste wood, no crystalline DDT residues remain on the sample surface observed utilizing optical microscopy. 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: 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.
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. 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 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. 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: 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.
UV nm femtosecond laser beam fs is used at 1kHz for the polymer surface irradiation. Different structures are generated depending on the laser dose. Also, Original 2D droplets 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.
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.
Optical, Thermal and Structural analysis of copper and titanium thin films with nm the thickness are achieved by applying accumulative pulses. Namely, the thermal properties are investigated by a pulsed photo-thermal technique PPT. The sample is irradiated heated under atmospheric pressure or vacuum by a homogenized excimer laser beam 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 MHz. The reflected signals are measured using very fast photodiodes. Discussion of the reflectivity and the thermal properties changes on copper and titanium thin films is detailed with respect to the laser beam parameters: Amin-Chalhoub, Applied Surface Science Djouadi, J ; Phys. 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.
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. 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. Considers the processes of ns-laser ablation of metal targets in the surrounding ambient gas. 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: 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. Successful highly sensitive material printing requires several technological developments, i. Specifically, the following issues will be addressed: Different sensitivities and selectivity to the selected analytes i. 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.
In this work we report the progress on the obtaining and characterization of antireflective AR coatings from dielectric oxides for high power laser systems. 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.
Moreover, the usage of HfO2 as bottom layer induces a nanostructured growth of the top layer. This decrease is most likely due to the fact that the top layer of material may contain some voids. 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 receiver is an nm thick molybdenum film on glass intended as back contact for CIGSe solar cells.
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. 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.
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.
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. Deposition was done in nitrogen pressure of 0. XRD patterns support this observation pointing to formation of small randomly oriented h-AlN crystallites.
AFM imaging reveals increasing surface roughness with degree of crystallinity in the films. In the presentation, the growth mechanism will be interpreted considering also our previous studies, where the laser fluence and nitrogen pressure were systematically changed.
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. 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.
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 bioactive glass nanoparticles by laser ablation of solids in open air LASOA. A CO2 laser wavelength nm , that operates both in CW and pulsed mode, was used as laser source in the experiments. Solid bulks of bioactive glass prepared by melt quench technique were used as targets to be ablated by laser in open air. The produced nanoparticles are mainly bioactive glass showing spherical shape and a diameter range from 10 to 80 nm.
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. 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. 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  and due to melting [3,4,6]. 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.
Chichkov, Applied Physics A , Chichkov, Journal of Laser Applications 24, Bulgakova, Applied Physics A 82, Yalisove, Applied Physics Letters , 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 , second harmonic generation in compound semiconductors , excitation of surface excited waves , or self-organization .
A strong correlation between beam area, the mean distance between defects , and the formation of high and low spatial frequency LIPSS was found. This is attributed to the high number of intrinsic defects of stainless steel compared to silicon. Bonse, Applied Surface Science , Haugen, Applied Physics Letters 82, Miyazaki, Optics Express 16, Bestehorn, Applied Physics A , — High intensity laser pulses can generate high densities of electrons in matter.
One technologically important follow-up process is the deterministic multiphoton-electron coupling . In the present work, the generation of high electron densities in a solid by high intensity femtosecond laser pulses  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 , materials machining in liquid contact, and the generation of colloidal solutions .
B 81 Kautek, ChemPhysChem http: 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. 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. 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.
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. 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. 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.
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. Laser assisted bulk material transformation doping, marking, crystallisation Read more Read less. Kindle Cloud Reader Read instantly in your browser. Product details File Size: Elsevier Science; 1 edition March 29, Publication Date: March 29, Sold by: Related Video Shorts 0 Upload your video.
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