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This paper describes high-resolution Surface Enhanced Raman Spectroscopy (SERS) analyses of fungicide Dithane DG (mancozeb) assisted by advanced Au and Ag nanostructures. Noble metal thin films were deposited on quartz substrates by pulsed laser deposition (PLD) technique and then annealed by a single laser pulse to produce nanostructures. The as prepared structures were used as active substrates for SERS analyses in order to detect the fungicide Dithane DG (mancozeb) at quantities at least one order of magnitude smaller than routinely applied in agricultural medicine. The investigation and results obtained express a relatively easy and inexpensive method additional to the existing analytical methods for detection of small amounts or residue of harmful pollutants. It is directly forwarded to preserve the quality of the environment and thus the human and animals’ health.

Medical grade polydimethylsiloxane (PDMS) elastomer is a biomaterial widely used in medicine and high-tech devices, e.g. MEMS and NEMS. In this work, we report an experimental investigation on femtosecond laser processing of PDMS-elastomer with near infrared (NIR), visible (VIS) and ultraviolet (UV) pulses. High definition trenches are produced by varying processing parameters as laser wavelength, pulse duration, fluence, scanning speed and overlap of the subsequent pulses. The sample surface morphology and chemical composition are investigated by Laser Microscopy, SEM and Raman spectroscopy, addressing the effects of the various processing parameters through comparison with the native materials characteristics. For all the laser pulse wavelengths used, the produced tracks are successfully metalized with Ni via electro-less plating method. We observe a negligible influence of the time interval elapsed between laser treatment and metallization process. Our experimental findings suggest promising perspectives of femtosecond laser pulses in micro- and nano-fabrication of hi-tech PDMS devices.

This article presents experimental investigations of effects of the process parameters on the medical grade polydimethylsiloxane (PDMS) elastomer processed by laser source with irradiation at UV (266 and 355 nm), VIS (532 nm) and NIR (1064 nm). Systematic experiments are done to characterize how the laser beam parameters (wavelength, fluence, and number of pulses) affect the optical properties and the chemical composition in the laser treated areas. Remarkable changes of the optical properties and the chemical composition are observed. Despite the low optical absorption of the native PDMS for UV, VIS and NIR wavelengths, successful laser treatment is accomplished due to the incubation process occurring below the polymer surface. With increasing of the fluence and the number of the pulses chemical transformations are revealed in the entire laser treated area and hence decreasing of the optical transmittance is observed. The incubation gets saturation after a certain number of pulses and the laser ablation of the material begins efficiently. At the UV and VIS wavelengths the number of the initial pulses, at which the optical transmittance begins to reduce, decreases from 16 up to 8 with increasing of the laser fluence up to 1.0, 2.5 and 10 J cm −2 for 266, 355 and 532 nm, respectively. In the case of 1064 nm the optical transmittance begins to reduce at 11th pulse incident at a fluence of 13 J cm −2 and the number of the pulses decreases to 8 when the fluence reaches value of 16 J cm −2 . The threshold laser fluence needed to induce incubation process after certain number of pulses of 8 is different for every wavelength irradiation as the values increase from 1.0 for 266 nm up to 16 J cm −2 for 1064 nm. The incubation and the ablation processes occur in the PDMS elastomer material during its pulsed laser treatment are a complex function of the wavelength, fluence, number of pulses and the material properties as well.

The paper presents results on laser nanostructuring of Ag thin films. The thin films are deposited on glass substrates by pulsed laser deposition technology. The as fabricated films are then annealed by nanosecond laser pulses delivered by Nd:YAG laser system operated at λ = 355 nm. The film modification is studied as a function of the film thickness and the parameters of the laser irradiation as pulse number and laser fluence. In order to estimate the influence of the environment on the characteristics of the fabricated structures the Ag films are annealed in different surrounding media: water, air and vacuum. It is found that at certain conditions the laser treatment may lead to decomposition of the films into a monolayer of nanoparticles with narrow size distribution. The optical properties of the fabricated nanostructures are investigated on the basis of transmission spectra taken by optical spectrometer. In the measured spectra plasmon resonance band is observed as its shape and position vary depending on the processing conditions. The fabricated structures are covered with Rhodamine 6G and tested as active substrates for Surface Enhanced Raman Spectroscopy (SERS).

This research is focused on investigation of coupled plasmonic/metal-semiconductor nanomaterials. A two-step laser-assisted method is demonstrated for formation of plasmonic Ag nanoparticles (NPs) distributed into porous metal–oxide semiconductors. The mosaic Ag-ZnO target is used for laser ablation and, subsequently, laser annealing of the deposited layer is applied. The plasmon resonance properties of the nanostructures produced are confirmed by optical transmission spectroscopy. The wurtzite structure of ZnO is formed with tilted c-axis orientation and, respectively, a mixed Raman mode appears at 580 cm−1. The oxygen pressure applied during a deposition process has impact on the morphology and thickness of the porous nanostructures, but not on the size and size distribution of AgNPs. The porous nanocomposites exhibited potential for SERS applications, most pronounced for the oxygen deficient sample, grown at lower oxygen pressure. The observed considerable SERS enhancement of R6G molecules on AgNP/ZnO can be attributed to the ZnO-to-molecule charge transfer contribution, enhanced by the additional electrons from the local surface plasmon resonance (LSPR) of AgNPs to the ZnO through the conduction band.

Data about the chemical status of poly(dimethylsiloxane) (PDMS) after nanosecond Q-switched Nd:YAG laser treatment with near infrared, visible and ultraviolet radiation are presented. The μ-Raman spectroscopy analyses reveal as irradiation result a new sharp peak of crystalline silicon. In addition, broad bands appear assigned to D band of amorphous carbon and G band of microcrystalline and polycrystalline graphite. The μ-Raman spectra are variable taken in different inspected points in the trenches formed by laser treatment. The XPS surface survey spectra indicate the constituent elements of PDMS: carbon, oxygen and silicon. The spectra of detail XPS scans illustrate the influence of the laser treatment. The position of Si 2p peaks of the treated samples is close to the value of non-treated except that irradiated by 1064 nm 66 pulses, which is shifted by 0.9 eV. Accordingly, a shift by 0.4 eV is noticed of the O 1s peak, which reflects again a stronger oxidation of silicon. The curve fitting of Si 2p and O 1s peaks after this particular laser treatment shows the degree of conversion of organic to inorganic silicon that takes place during the irradiation.

This work presents results on direct nanostructured film fabrication by pulsed laser deposition (PLD) of gold in air at atmospheric pressure. Due to specific features of the laser-induced plume evolution at these conditions, the deposited film has a porous structure composed of well defined nanoparticles aggregates. The study based on scanning and transmission electron microscopy images of the deposited material at different processing conditions reveals that these nanoparticle aggregates are formed into the ablated plume due to intensive collisions. The obtained structures show characteristic optical spectra related to excitation of plasmons and can be directly used in practical applications as surface enhanced Raman spectroscopy (SERS) and sensors devices.

The paper presents a study on the fabrication of ZnO nanostructures by applying a pulsed laser deposition technique in air at atmospheric pressure (in open air). The laser ablation of a ZnO target was performed by a nanosecond Nd:YAG laser system operated at the wavelengths of 355, 532 and 1064 nm. In open air, the ablation process leads to a direct deposition of nanoparticles and nanoparticle aggregates formed in the plasma plume. The deposition of the nanostructured material on the substrate resulted in the growth of a highly porous structure. The influence was investigated of the wavelength used for ablation on the morphology, composition and optical properties of the samples. The ultraviolet ablation resulted in deposition of a structure which mainly consists of nanoparticle aggregates and separate nanoparticles. Deposition by visible light formed a highly porous structure consisting of aggregated nanoparticles. Conducting the ablation process with infrared radiation resulted in the growth of a complex 3D structure consisting of large nanoparticle aggregates. The presence of a small amount of nitrogen was detected in all samples independently of the wavelength used for ablation. It was found that the different wavelengths used for ablation lead to fabrication of ZnO structures with different morphology and different types of surface defects, which defines the photoluminescence properties of the samples. The porous structure observed in the ZnO samples, combined with their optical properties, suggests that such nanostructures could be used for efficient fabrication of sensor devices.

In this work, results on laser processing of thin metal films deposited on paper are presented. Au, Ag, Cu, and Ni films are deposited by classical pulsed laser deposition method on different paper types—standard printer, glossy, and silicone paper. The produced films are then processed by nanosecond pulses delivered by Nd:YAG laser system operating at the basic wavelength of 1064 nm. 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 a monolayer of spherical 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 nanostructures with application in low cost sensor device fabrication.

This study presents results on pulsed laser ablation of gold target immersed in different liquids. In the experiments chloroform, toluene and ethanol are used as liquid media for the laser ablation. Two different wavelengths: the fundamental (1064 nm) and second harmonic (532 nm) of a Nd:YAG laser, are utilized to produce various colloids. The optical properties of the colloids were evaluated by optical transmittance measurements in the UV–Vis spectral range. The morphology of the colloidal nanoparticles created and the evaluation of their size distribution are investigated by transmission electron microscopy. The selected area electron diffraction is employed for chemical phase identification of the created nanostructures. Ablation in chloroform resulted in formation of spherical and spheroidal gold nanoparticles with the similar mean size at both laser wavelengths used—11.5 nm at 1064 and 9.3 nm at 532 nm. Nanoparticles with smaller mean size (below 5 nm) in the case of ablation in toluene were observed. Spherical nanoparticles with mean diameter of 7.7 nm produced by 1064 nm and thin elongated nanostructures with thickness of about 5 nm using 532 nm are observed in the case of ablation in ethanol. An additional laser irradiation of the colloids demonstrated the changing of the optical properties and size distribution of the nanostructures produced by ablation in ethanol and chloroform. The irradiation of toluene-based colloid does not induce observable change of the colloid properties.

In this work laser-assisted methods for metal nanostructures formation and their application as active substrates in Surface Enhanced Raman Spectroscopy are presented. The nanostructures are fabricated by laser processing of gold thin films deposited on low cost substrates as glass, ceramic, polymer and paper. The films are deposited by classical PLD technology. The produced films are then processed by nanosecond pulses delivered by nanosecond Nd:YAG laser system. At certain conditions the laser treatment leads to formation of discrete nanostructure on the substrate surface. Femtosecond Pulsed Laser Deposition in air is also applied for direct deposition of gold nanostructure. In another set of experiments gold nanoparticle colloids are fabricated by laser ablation of gold target in chloroform. The fabricated structures are then tested as active systems in SERS, as detection of pesticides (DDT), nitrates (NH4NO3), and drugs (Methylene blue) is demonstrated. The obtained results show that these nanostructures can be efficiently used in the detection and monitoring of materials with a high social impact.

Laser ablation of a gold thin film irradiated by ultrashort pulses is studied using molecular-dynamics simulations, and compared with that of a bulk target. A film thickness comparable to the ballistic electron depth in gold (≈ 100 nm) is considered, evidencing a significant change of the temperature spatial profile inside the target material, which eventually influences the material decomposition. Particular emphasis is given to the process of nanoparticle generation. The simulations indicate a more uniform heating of the sample in the case of the thin film, which is accompanied by a more homogeneous size distribution of the nanoparticles produced in the ablation process. An experimental characterization of the ultrashort-pulse ablation process is also carried out. The produced nanoparticles are collected on suitable substrates, and atomic force microscopy analysis of less than one layer deposits is performed. An ≈ 2 × narrowing of the nanoparticles equivalent to spherical diameter size distribution is observed in the case of ablation of the gold thin film, in fairly good agreement with the theoretical predictions. Moreover, interesting changes of the nanoparticle shape are evidenced, which are correlated to the changes in the nanoparticle ablation plume dynamics, as studied by time-gated imaging of its self-emission. Our findings suggest ultrashort-pulse laser ablation of thin films as a viable route to achieve a more uniform nanoparticle size distribution.

Contamination-free Ag nanoparticles were produced by nanosecond pulsed laser ablation (10 Hz repetition rate, 15 ns pulse duration) of a solid target immersed in double distilled water. The size distribution observed of the NPs is wider compared to those obtained by other preparation methods, mainly chemical. To modify it and make the NPs more appropriate for biological application, the fabricated suspensions were irradiated by an unfocused laser beam. The fundamental wavelength (λ = 1064 nm) of a Nd:YAG laser system was used for Ag NPs preparation. It lies outside their surface plasmon absorption band and was chosen to avoid self-absorption during ablation by already formed NPs. Excluding a possible absorption in the preparation stage provides a better control of the irradiation influence. The following irradiation of the suspension obtained was performed by the third (λTHG = 355 nm) harmonic of the laser system, which was chosen due to its positioning within the corresponding surface plasmon absorption band. The changes of the NPs characteristics caused by different laser fluence and duration of irradiation were traced by transmission electron microscopy (TEM) and confirmed by optical transmission measurements in the near UV and the visible region. A considerable narrowing (by about of a factor of three) of the surface plasmon extinction band was achieved, which is evidence of narrowing of the particles size distribution and approach of their shape to the ideal spherical.

A study is presented of Au nanoparticles (NPs) created by nanosecond pulsed laser ablation of a solid target in double distilled water. The influence was examined of the laser wavelength on the size, shape and optical properties of the resulting NPs. Three different wavelengths: the fundamental (λ = 1064 nm), second (λSHG = 532) and third (λTHG = 355) harmonic of a Nd:YAG laser at the same fluence were utilized to produce various colloids. Ablation at the wavelength of 532 nm was investigated in more detail to reveal the influence of self-absorption by the already created NPs on their characteristics. The colloid produced was irradiated by λirrad = 532 nm (laser energy 40 mJ) at different times up to 25 min after the end of ablation. The initial structure of welded NPs forming wires was modified. Transmission electron microscopy and optical transmission measurements were used to evaluate the shape and size distribution of the NPs.

In this paper we present a laser-based method for metal nanostructures formation on flexible substrates. The analysis of the obtained structures is focused on their optical properties. The nanostructures are fabricated by laser processing of gold thin films. The films are deposited on PMMA and PVC substrates by classical PLD technology. The produced films are then annealed by nanosecond pulses delivered by Nd:YAG laser system operated at λ = 355 nm. At certain conditions the laser treatment leads to formation of discrete nanostructure on the substrate surface. The optical properties of samples fabricated at different conditions are examined by optical spectroscopy. Bending of the substrates at different angles is used to modify the characteristics of the produced structure which leads to change of its optical properties. In this way the plasmon band of the obtained nanostructures can be efficiently tuned in a range of about 30 nm. The experiments of using produced structures in Surface Enhanced Raman Spectroscopy show that they can be an efficient alternative of the already developed.

The optical properties of gold nanoparticle clusters are presented from the point of view of their applications in biophotonics, where the absorption and scattering spectra are crucial. Generalised multiparticle Mie theory and finite difference time domain (FDTD) technique are used for theoretical description of the far- and nearfield optical properties of two dimensional nanoparticle ensembles. The system under consideration consists of spherical gold nanoparticles from 20 to 200 nm in diameter, forming 2D clusters in water. The properties of the far-field absorption and scattering spectra as a function of the cluster size, particle dimensions, and interparticle distance are investigated for ordered hexagonal structure of the particle arrays. It is found that the absorption efficiency can be shifted to the IR spectral range by increasing array size and decreasing interparticle distance. The increase in the array size also results in enhancement of the scattering efficiency while the absorption is reduced. The near-field intensity distribution is inhomogeneous over the array, as formation of zones with intensity enhancement of about two orders of magnitude is observed in specific areas. The optical properties of an ensemble whose configuration is reproduced from real experiments of gold nanoparticle deposition onto cancer cells are also presented. The results obtained can be used in designing of nanoparticle arrays with applications in biophotonics, bioimaging and photothermal therapy.

Results are presented on the synthesis and characterization of nanocomposite Ag/ZnO heterostructures on fused quartz substrates. The experiments were performed by pulsed laser deposition (PLD) using a third harmonic Nd:YAG laser in a vacuum chamber. The ablation of a rotated Ag target was followed by laser modification of the deposited layer and subsequent deposition of ZnO. The process factors, such as the silver film thickness and the post-deposition annealing procedures, were varied in view of controlling the diameter and size distribution of the Ag nanoparticles. The annealing regimes were modified by varying the laser irradiation energy on the Ag layers. The effect on the Ag/ZnO properties is discussed. It is demonstrated that the photoluminescence intensity of ZnO nanolayers is significantly enhanced by plasmon absorption in the Ag nanoparticles and a shift to the lower wavelengths.

Preparation of noble metal nanoparticle (NPs) colloids using pulsed laser ablation in water has an inherent advantage compared to the different chemical methods used, especially when biological applications of the colloids are considered. The fabrication method is simple and the NPs prepared in this way are contamination free. The method of laser ablation of a solid target in water is applied in the present work in order to obtain gold and silver NP colloids. The experiment was preformed by using the fundamental wavelength (1064 nm) of a Nd:YAG laser system. The target immersed in double distilled water was irradiated for 20 min by laser pulses with duration of 15 ns and repetition rate of 10 Hz. The sedimentation and aggregation of NPs in the colloids, stored at constant temperature, as a function of the time after preparation were investigated. The analyses are based on optical transmission spectroscopy in UV and vis regions. The change of the plasmon resonance wavelength as a function of time was studied. Zeta potential measurement was also utilized to measure the charge of the NPs in the colloids. The size distribution of the NPs and its change in time was determined by transmission electron microscopy (TEM). On the basis of the results obtained, the optimal conditions of post fabrication manipulation with gold and silver colloids are defined in view of producing stable NPs with a narrow size distribution.

The paper presents results on laser nanostructuring of bimetallic thin films. The thin films are deposited by classical on-axis pulsed laser deposition technology by using targets consisted of two sections composed of different metals. Using this technique gold/nickel or gold/silver thin films are deposited on quartz substrate. By changing the area of the different sections of the target, thin films with different concentrations of the two metals are obtained. The as fabricated films are then annealed by nanosecond laser pulses delivered by Nd:YAG laser system operated at λ = 355 nm. The modification of the produced films is studied as a function of the parameters of the incident irradiation as pulse number and laser fluence, the composition of the thin films, and characteristics of the environment. It is found that the laser annealing may lead to nanostructuring of the films as at certain conditions the thin films are decomposed into a monolayer of nanoparticles with narrow size distribution. The performed EDX analyses indicated that the fabricated particles are composed by a bimetallic system of the basic metals used. The extinction spectra of the obtained structures show plasmon excitations as the resonance wavelength can be efficiently tuned in a wide range by changing the ratio of the basic metals in the films. The obtained structures can be used in SERS and magneto-optics.

We study semi-regular arrays of Au nanoparticles (NP) obtained via UV laser irradiation of thin Au films on glass substrate. The NP structures are prepared from films of a thickness up to 60 nm produced by discharge sputtering or pulsed laser deposition, and annealed by nanosecond laser pulses at 266 or 308 nm, respectively, at fluencies in the range of 60–410 mJ/cm2. For the rare- and close-packed NP structures, consistent description of optical properties is derived from microscopic observation, measurements of the absorption, and Raman spectra, and modeling of the near-field intensity distributions. The absorption bands centered at 540–570 nm are ascribed to resonant absorption of the surface plasmons. For the band positions, half widths, and intensities, the dependence on the NP shape (partial spheres), size, size distribution, and also excitation energy is observed. The structures are characterized by markedly reduced dephasing times of ∼3 fs. It is shown, that laser annealing of thin Au films provides reliable and cost effective method for controlled preparation of semi-regular NP arrays favorable for photonic applications.

A study is presented of the properties of Ag nanoparticles produced by nanosecond pulsed laser ablation in twice-distilled water. An Ag target was immersed in the liquid and irradiated by the fundamental, second, third and fourth harmonics of a Nd:YAG laser system to create different colloids. Two specific boundary values of the laser fluence were applied for each wavelength. The properties of the nanoparticles at different wavelengths of the laser radiation were examined. The characterization of the colloids was performed immediately after their fabrication. Spherical and spherical-like shapes of the nanoparticles created were established. The formation of nanowires was observed when the second and the third harmonics of the laser were used. It is connected with self-absorption of the incident laser light from the already-created nanoparticles and depends also on the laser fluence. The size distribution of the nanoparticles is estimated by transmission electron microscopy. Generally, their mean size and standard deviation decreased as the wavelength of the incident laser light was increased and increased with the increase of the laser fluence. The substantial discrepancy between the results already commented on for both characteristics considered and others, obtained by dynamic light scattering, is discussed. The structure of the nanoparticles was established to be single and polycrystalline, and the phase composition in both cases is identified as consisting of cubic silver. The nanoparticles are slightly oxidized.

Thin ZnO nanostructured films were produced by pulsed laser deposition (PLD) for surface enhanced Raman spectroscopy (SERS) studies. The experimental conditions used for preparation of the samples were chosen to obtain different types of ZnO nanostructures. The Raman spectra of rhodamine 6G (R6G) were measured at an excitation wavelength of 785 nm after coating the ZnO nanostructures with a thin Au layer. The influence of the surface morphology on the Raman signal obtained from the samples was investigated. High SERS signal enhancement was observed from all Au-coated ZnO nanostructures.

ZnO nanorods were produced by pulsed laser deposition (PLD). Drops of nanoparticle colloid (gold or silver) were placed on silica substrates to form growth nuclei. All nanoparticles were monocrystalline, with well-defined crystal surfaces and a negative electrical charge. The ZnO nanorods were produced in an off-axis PLD configuration at oxygen pressure of 5 Pa. The growth of the nanorods started from the nanoparticles in different directions, as one nanoparticle could become a nucleus for more than one nanorod. The low substrate temperature used indicates the absence of a catalyst during the growth of the nanorods. The diameters of the fabricated 1-D ZnO nanostructures were in the range of 50–120 nm and their length was determined by the deposition time.

Pulsed laser ablation of Ag and Au targets, immersed in double-distilled water is used to synthesize metallic nanoparticles (NPs). The targets are irradiated for 20 min by laser pulses at different wavelengths—the fundamental and the second harmonic (SHG) ( λ = 1064 and 532 nm, respectively) of a Nd:YAG laser system. The ablation process is performed at a repetition rate of 10 Hz and with pulse duration of 15 ns. Two boundary values of the laser fluence for each wavelength under the experimental conditions chosen were used—it varied from several J/cm 2 to tens of J/cm 2 . Only as-prepared samples were measured not later than two hours after fabrication. The NPs shape and size distribution were evaluated from transmission electron microscopy (TEM) images. The suspensions obtained were investigated by optical transmission spectroscopy in the near UV and in the visible region in order to get information about these parameters. Spherical shape of the NPs at the low laser fluence and appearance of aggregation and building of nanowires at the SHG and high laser fluence was seen. Dependence of the mean particle size at the SHG on the laser fluence was established. Comments on the results obtained have been also presented.

Theoretical and experimental results on the heating process of gold nanoparticles irradiated by nanosecond laser pulses are presented. The efficiency of particle heating is demonstrated by in-vitro photothermal therapy of human tumor cells. Gold nanoparticles with diameters of 40 and 100 nm are added as colloid in the cell culture and the samples are irradiated by nanosecond pulses at wavelength of 532 nm delivered by Nd:YAG laser system. The results indicate clear cytotoxic effect of application of nanoparticle as more efficient is the case of using particles with diameter of 100 nm. The theoretical analysis of the heating process of nanoparticle interacting with laser radiation is based on the Mie scattering theory, which is used for calculation of the particle absorption coefficient, and two-dimensional heat diffusion model, which describes the particle and the surrounding medium temperature evolution. Using this model the dependence of the achieved maximal temperature in the particles on the applied laser fluence and time evolution of the particle temperature is obtained.

In this work we show the properties of the electromagnetic field in the vicinity of a monolayer nanoparticle array on SiO2 substrate. The nanoparticle array is produced by a simple experimental procedure, where thin gold and silver films are deposited on a substrate by pulsed laser deposition technique and they are annealed by nanosecond laser pulses. At certain conditions the laser annealing leads to a homogeneous decomposition of the film into nanoparticles with diameters in the range of few tens of nanometers. Using FDTD simulations the near field distribution in array structures taken from SEM images are obtained. The distribution shows presence on “hot spots” where the near field intensity is enhanced more than two orders of magnitude compared to the incident one. The existence of enhanced field intensity is assumed to be the main reason on enhancement of the Raman scattering signal obtained experimentally using the produced structures as active substrates.

Theoretic and experimental results on the heating process and near field localization arising when gold nanoparticles are irradiated by ultrashort laser pulses are presented. The system under consideration consists of nanoparticles with radius of 20, 40, or 100 nm in vacuum or deposited on different substrates. Substrate materials with different dielectric properties are used to sense and visualize the nanoparticle heating and near electromagnetic field distribution. The theoretic analysis is based on two-temperature heat model for estimation of the nanoparticle temperature and Finite Difference Time Domain (FDTD) method for description of the near field distribution in the vicinity of the particles. It is found that at even moderate laser fluences, particle temperature can reach a value sufficient for bubble formation in biological tissues. The analysis of the near field distribution shows that when particle is deposited on substrate surface, the dielectric properties of the substrate define the localization and enhancement of the near field intensity. The efficiency of this process determines the contribution of particle heating or near field intensity enhancement in the surface modification process. The localization of the near field intensity in the vicinity of the contact point between the particle and substrate is proved experimentally for metal and silicon substrates, where the experimentally obtained surface modifications resemble the theoretically predicted intensity distribution.

In this work, erbium, and erbium and ytterbium co-doped YVO 4 waveguiding thin films were deposited on amorphous SiO 2 substrates by pulsed laser deposition (PLD) and ultraviolet-assisted pulsed laser deposition (UVPLD). The influence of the deposition technique on the structure, morphology, and optical properties of the films was investigated. At lower dopant concentrations the films prepared by UVPLD show better crystallinity and optical properties. All the samples show preferred orientation of the (001) zone axes parallel to the substrate surface. The polycrystalline samples show difference in the refractive indexes ∆ n (∆ n = n TE − n TM ) for the TE and TM polarizations.

Pulsed laser deposition technique was used to fabricate successfully nanostructured optical waveguide films of TiO2 and WO3 − x for gas-sensing applications. High-quality mode spectra, consisting of well-defined bright mode lines were observed in the samples with smooth surface. Films' structural, morphological and optical properties as well as the chemical composition were investigated by using x-ray diffraction, scanning electron and atomic force microscopy, UV–VIS–NIR, m-line and x-ray photoelectron spectroscopy, respectively. Gas sensitivity was investigated at room temperature using m-line spectroscopy technique on basis of reversible variations of the refractive index of the samples under gas exposure. Testing scheme recording the bright m-line shift as optical response was proposed.

We demonstrate the possibility to fabricate wire structures composed by arranged magnetic particles using pulsed laser deposition (PLD) in the presence of a magnetic field. Ablation of Ni and Co targets was performed in air by nanosecond laser pulses delivered by a Nd:YAG laser system oscillating at 355 nm. Due to the high density of the ambient, particles and clusters were formed by condensation in the plasma plume close to the target. The strong deceleration of the ablated material under these conditions further benefited the efficiency of applying a magnetic field to the plume. We also studied the effect of the target-to-substrate distance and the ambient pressure on the morphology of the deposited structures.

The medical-grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial in medicine for preparation of high-tech devices because of its remarkable properties. In this paper, we present experimental results on surface modification of PDMS elastomer by using ultraviolet, visible, and near-infrared ns-laser system and investigation of the chemical composition and the morphological structure inside the treated area in dependence on the processing parameters – wavelength, laser fluence and number of pulses. Remarkable chemical transformations and changes of the morphological structure were observed, resulting in the formation of a highly catalytically active surface, which was successfully functionalized via electroless Ni and Pt deposition by a sensitizing-activation free process. The results obtained are very promising in view of applying the methods of laser-induced micro- and nano-structuring and activation of biopolymers' surface and further electroless metal plating to the preparation of, e.g., multielectrode arrays (MEAs) devices in neural and muscular surface interfacing implantable systems.

This study deals with the development of a novel technique for formation of advanced Ag nanostructures (NSs) to be applied to high-resolution analyses based on surface enhanced Raman scattering (SERS). It has direct bearing on human health and food quality, e.g., monitoring small amount or traces of pollutants or undesirable additives. Three types of nanostructured Ag samples were produced using ion-beam deposition at glancing angle (GLAD) on quartz. All fabricated structures were covered with BI-58 pesticide (dimethoate) or Rhodamine 6G (R6G) for testing their potential for use as substrates for (SERS).

In this work the near field properties of a single gold nanoparticle embedded in transparent host medium are investigated theoretically. The analysis of the electromagnetic field in the near field zone is obtained by finite difference time domain (FDTD) simulation technique. The nanoscale system consists of a transparent layer in which a gold particle with diameters of D = 200 or 80 nm is embedded, is situated on a substrate surface. Laser pulse at wavelength of 800 nm irradiates normally this system. It is found that the field in the vicinity of the particle is enhanced, and at a certain condition the zone with the highest enhancement is localized on the substrate surface. Furthermore, the near field characteristics are found to be controllable by the dielectric properties of the host material, substrate, parameters of the incident irradiation and particle size. With the increase of the refractive index of the host medium, both the magnitude of the near field on the substrate and the characteristic size of the field enhanced zone decrease. The influence of the particle size and polarization of the incident laser irradiation on the near filed properties of the system are also presented. The proposed configuration can be applied for a multiple nanoprocessing and an integrated near field source with a spatial resolution of D/3.

Erbium, and erbium and ytterbium co-doped YVO4 waveguiding films were deposited on MgO/Si substrates by PLD. The samples were post-annealed at two different temperatures in air atmosphere. The influence on the crystalline structure and waveguiding properties of the films at these annealing temperatures for two dopant concentrations was investigated. Layers annealed up to 900 °C are polycrystalline. The dominant fraction of YVO4 crystallites exhibited preferred orientation of the (0 0 1) zone axes parallel to the substrate surface. The polycrystalline samples show difference in the refractive indexes Δn (Δn = nTE − nTM) for TE and TM polarizations.

Nanoparticles (NPs) creation by pulsed-laser ablation of targets in a liquid environment has recently become a promising technique, which has several relative advantages, such as simplicity and low cost. This technique was employed in the present work for preparation of TiO x NPs suspension by ablation of metal Ti targets into twice-distilled water. A second harmonic generation (SHG) pulsed Nd:YAG laser was used in the experiments. Preferential formation of spherical NPs and their TiO x nature was established. Aggregation of the created particles during aging was found. Transition of the NPs’ structure from amorphous to crystalline with increasing the laser energy was revealed. A difference was observed in the transmittance of the suspensions obtained depending on the laser intensity.

Vanadium-doped ZnO films (Zn1−xVxO, where x = 0.02, 0.03, 0.05 and 0.07), were formed from ceramic targets on c-cut sapphire substrates using pulsed laser deposition at substrate temperature of 600 °C and oxygen pressure of 10 Pa. In order to clarify how the vanadium concentration influences the films’ properties, structural and magnetic investigations were performed. All films crystallised in wurtzite phase and presented a c-axis preferred orientation at low concentrations of vanadium. The results implied that the doping concentration and crystalline microstructure influence strongly the system's magnetic characteristics. Weak ferromagnetism was registered for the film with the lowest doping concentration (2 at.%), which exhibited a ferromagnetic behavior at Curie temperature higher than 300 K. Increasing the vanadium content in the film caused degradation of the magnetic ordering.

In this work the optical and the gas sensing properties of thick TiO 2 waveguide films, produced by pulsed laser deposition, were investigated by m -line spectroscopy. The films were deposited on (0 0 1) SiO 2 substrates at temperature of 100 °C. The thickness of the films was measured to be in the range from 650 to 1900 nm and the roughness increases from 5 to 14.6 nm. High quality mode spectra, consisted of thin and bright TE and TM modes, were observed in the films with thickness up to 1200 nm. All the films revealed anisotropic optical properties. Gas sensitivity of the films to CO 2 was examined at room temperature on the basis of the variations of the refractive index. CO 2 concentration of 3 × 10 4 ppm was detected, which corresponds to a refractive index variation of about 1 × 10 −4 . The crystal structure and the optical transmittance of the films were also presented and discussed.

In this work, thin ZnO films have been produced by pulsed laser deposition on side-polished fiber for optical gas sensor applications. The influence was investigated of the processing parameters, such as substrate temperature and oxygen pressure applied during deposition, on the sensitivity to ammonia of the sensing element. A shift of the spectral position of the resonance minimum to the longer wavelengths was observed at room temperature for the sample prepared at 150 °C substrate temperature and 20 Pa oxygen pressure. Spectral changes in the range 0.16–1.13 nm for NH 3 concentrations between 500 and 5000 ppm were also observed.

The purpose of the present investigation is the fabrication of undoped and palladium doped indium tin oxide films by pulsed laser deposition and the analyses of their optical, waveguide and structural properties in view of optical sensor applications. The films are deposited at oxygen pressure from 5 to 20 Pa and substrate temperature between 200 and 450 °C. Palladium is used as a dopant since it is critical in improving the sensor's properties. The X-ray diffraction spectra show that all films are polycrystalline with preferential [1 1 1] orientation. The optical transmittance measured in the visible region has maximum values of 85–90% for films grown at oxygen pressure 15 Pa independently of the substrate temperature used. SEM, AFM and optical and investigations revealed that indium tin oxide films with 1 wt.% Pd have higher transmittance and better surface morphology than those with 3 wt.% Pd concentration. ITO films with minimum propagation losses of 2 dB cm −1 were deposited at substrate temperature 200 °C and oxygen pressure 5 Pa, but doped ITO films with minimum propagation losses were obtained at 400 °C and 15 Pa.

In this work, thin YVO 4 films were deposited on amorphous SiO 2 substrates by pulsed laser deposition (PLD). Ceramic targets of pure and doped (Er and Er, Yb) YVO 4 were prepared and used for ablation. The influence of the substrate temperature and oxygen pressure applied during the depositions was investigated. Crystalline films were obtained at temperatures higher than 500 °C. The films with the best crystallinity were obtained at 5 Pa oxygen pressure and 700 °C substrate temperature. All the films are transparent in the visible and near infrared region of spectra. The crystalline samples show difference in the refractive indexes Δ n (Δ n = n TE − n TM ) for the TE and TM polarizations. It was evaluated to be about 0.08.

Symposium on Laser Interaction with Advaned Materials: Fundamentals and Applications, Lille, FRANCE, 2014; International audience; Laser-assisted method for fabrication of nanoparticles on the surface of ceramic substrate is presented. The method is based on laser dewetting of thin metal film deposited on the substrate. Using this technique, gold nanoparticles on alumina ceramic surface are fabricated. It is shown that the processing parameters can influence the properties of the fabricated structure, as at certain conditions a homogeneous cover of nanoparticles with narrow size distribution can be achieved. The processed surfaces are tested as substrates in surface enhanced Raman spectroscopy of a standard dye. The efficiency of the substratesis estimated by the ability of detection of the dye at nM concentration and it is compared to that of thin gold film on ceramic substrate. The strongest enhancement is observed for the sample where Au film is not completely decomposed and the structure consists of thin film and nanoparticles aggregates. The proposed method has potential application in fabrication of cheap and reliable substrates for Raman spectroscopy analysis with high sensitivity and also in catalysis. (C) 2014 Elsevier B.V. All rights reserved.

Medical grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial as encapsulation and/or as substrate insulator carrier for long term neural implants because of its remarkable properties. Femtosecond (λ = 263 and 527 nm) and nanosecond (266 and 532 nm) laser processing of PDMS-elastomer surface, in air, is investigated. The influence of different processing parameters, including laser wavelength, pulse duration, fluence, scanning speed and overlapping of the subsequent pulses, on the surface activation and the surface morphology are studied. High definition tracks and electrodes are produced. Remarkable alterations of the chemical composition and structural morphology of the ablated traces are observed in comparison with the native material. Raman spectra illustrate well-defined dependence of the chemical composition on the laser fluence, pulse duration, number of pulses and wavelength. An extra peak about ∼512–518 cm−1, assigned to crystalline silicon, is observed after ns- or visible fs-laser processing of the surface. In all cases, the intensities of Sisingle bondOsingle bondSi symmetric stretching at 488 cm−1, Sisingle bondCH3 symmetric rocking at 685 cm−1, Sisingle bondC symmetric stretching at 709 cm−1, CH3 asymmetric rocking + Sisingle bondC asymmetric stretching at 787 cm−1, and CH3 symmetric rocking at 859 cm−1, modes strongly decrease. The laser processed areas are also analyzed by SEM and optical microscopy. Selective Pt or Ni metallization of the laser processed traces is produced successfully via electroless plating. The metallization process is not sensitive with respect to the time interval after the laser treatment. DC resistance is measured to be as low as 0.5 Ω mm−1. Our results show promising prospects with respect to use such a laser-based method for micro- or nano-fabrication of PDMS devices for MEMS and NEMS.

18th International School on Quantum Electronics (ISQE) - Laser Physics and Applications, Sozopol, BULGARIA, SEP 29-OCT 03, 2014; International audience; In this paper we show an experimental procedure for fabrication of metal nanoparticle arrays on metal substrates. The nanostructures are fabricated by laser processing of thin metal films. The films are deposited on the metal substrates by classical PLD technology. The as deposited films are then annealed by nanosecond pulses delivered from a THG Nd:YAG laser system (lambda = 355 nm). At certain conditions, the laser treatment leads to a formation of discrete nanoparticle structure on the substrate surface. The optical properties of samples fabricated at different conditions and having different characteristics of the nanostructures are examined by optical spectroscopy measurement. Such analysis shows that the optical spectra of the obtained nanostructures are characterized by plasmon excitation. Finite difference time domain (FDTD) model is used for theoretical description of the near field optical properties of the fabricated nanoparticle arrays. The simulation demonstrates high efficiency of the fabricated structures in enhancement of the near field intensity. The great enhancement observed in the Raman spectra of Rhodamine 6G deposited on the fabricated samples makes such structures very appropriate for applications in Surface Enhanced Raman Spectroscopy (SERS). The produced systems can be also applied in plasmonic solar cells (PSC).

Classical molecular dynamics simulation technique is applied for investigation of the iron ablation by ultrashort laser pulses at conditions of deep hole for the first time. Laser pulse duration of 0.1 ps at wavelength of 800 nm is considered. The evolution of the ablated material in deep hole geometry differs completely from the free expansion regime as two major mechanisms are important for the final hole shape. The first one is the deposition of the ablated material on the walls, which narrows the hole at a certain height above its bottom. The second mechanism is related to ablation of the material from the walls (secondary ablation) caused by its interaction with the primary ablated particles. Properties of the secondary ablated particles in terms of the velocity and the angular distribution are obtained. The material removal efficiency is estimated for vacuum or in Ar environment conditions. In the latter case, the existence of well-defined vapor cloud having low center of the mass velocity is found. The processes observed affect significantly the material expulsion and can explain the decrease of the drilling rate with the hole depth increase, an effect observed experimentally.

A theoretical model is developed and a molecular dynamics simulation technique is applied for the description of ultrashort laser ablation of metals. The ablation of Al, Ni, and Fe using 0.1, 0.5 and 5 ps laser pulses at wavelengths of 248 and 800 nm is studied. The process is investigated at fluences up to 0.5 J/cm2. The analysis based on the temporal evolution of the ablation, the temperature, and the pressure distributions into the material reveals that a thermo-mechanical mechanism (spallation) takes place near the threshold. However, phase explosion is found to be the dominant mechanism of material removal at fluences higher than several hundreds of mJ/cm2. The influence of the laser parameters (wavelength and pulse duration) is obtained and discussed. The ablation depth as a function of the laser fluence and the ablation threshold value are evaluated and compared with the experimental data available. Good agreement between the theory and experiments is observed.

The influence of the pair Morse potential and the embedded-atom method (EAM) based potential on the description of the properties and the ultrashort laser ablation process of Fe by molecular dynamics (MD) simulation technique is studied. The accuracy of both potentials in evaluation of the melting temperature, the linear thermal expansion coefficient and the compression behavior of Fe is estimated. The EAM potential is found to give more precise description of the properties of Fe than the Morse one. The melting temperature is overestimated only 2% in the case of EAM and 24% for the Morse potential, respectively, compared to the experimental value. A discrepancy in the presentation of the elastic properties is also observed, as it is more pronounced in the case of Morse potential. The MD simulation of laser ablation of iron is performed for ultrashort laser pulses ( λ = 800 nm) with duration of 100 fs and at fluences below the ablation threshold up to 1 J/cm 2 . Analysis of the mechanism of ablation, evolution of the process, the temperature and the pressure distributions in the material is made.

Thin Er3+, Yb3+ co-doped Y2O3 films have been grown on (001) SiO2 substrates by pulsed laser deposition from ceramic targets. The influence of the active ion concentration and processing parameters on the structure, cathodoluminescent (CL) spectra and optical properties of the films have been investigated. The films were prepared in an oxygen atmosphere at pressures of 0.01 and 0.1 mbar and at 500°C substrate temperature. Blue, green and red light emissions centred at 408 nm, 562 nm and 660 nm, respectively, and an infrared (IR) spectrum centred at 1.54 µm were measured. The intensities of the CL peaks strongly depend on the Er and Yb ion concentration in the films and their ratio. An increase in Yb content at a fixed Er concentration leads to a decrease in the CL intensity in the visible range. It is higher for the films deposited at 0.1 mbar, which correlates with the better crystallinity obtained. Despite their better crystallinity, the films prepared at 0.01 mbar have a slightly higher optical transmission in the visible and near-IR range, which corresponds to the smoother surface and lower absorption measured.

A molecular dynamics model is applied to study the formation and the early stages of ejection of material in ultra-short laser ablation of metals in vacuum. Simulations of the ablation process for iron at a pulse duration of 0.1 ps and at different laser fluences are performed. Different features of the ejection mechanism are observed below, near, and above the ablation threshold. The last is estimated as approximately 0.1 J/cm2. The structure of the ablated material is found to depend on the applied laser fluence. The expanded plume consists mainly of large clusters at fluences near to the threshold. With the increase of the laser fluence the presence of the large clusters decreases. Clear spatial segregation of species with different sizes is observed in the direction normal to the surface several tens of picoseconds after the laser pulse onset. The angular distribution of the ejected material is estimated for different regimes of material removal. Above the ablation threshold the distribution is forward peaking.

Textured (1 1 0)Nd:KGW optical waveguides are grown on CeO 2 /Si substrates by pulsed laser deposition. Ceria buffer layer is prepared on (1 0 0)Si substrates by KrF excimer laser ablation of Ce 0.9 Gd 0.1 O 2 ceramic target. The (1 0 0) or (1 1 1) orientation of CeO 2 depends on the deposition conditions. The Nd:KGW films are prepared by ablation of K-rich ceramic targets in O 2 or Ar. The influence of the synthesis conditions (O 2 or Ar pressure and substrate temperature) and the orientation of the CeO 2 buffer layer on the crystallinity of the Nd:KGW films are studied. Better results are obtained when deposited on (1 0 0)CeO 2 /(1 0 0)Si. The as-grown films are optically active. The crystallinity improves and the intensity of the emission spectra increases upon annealing at 700 °C in air. The emission spectra of Nd:KGW films are demonstrated for the main Nd transitions in 0.85–1.45 μm spectral range. Waveguide loss as low as 3.3 dB cm −1 is measured.