ArF Excimer Laser Irradiation Research Articles

Cu-Au core-shell nanostructures induced by ArF excimer laser irradiation

In this paper, Cu-Au nanospherical structures were formed on glass surfaces by nanosecond UV laser irradiation. ArF laser pulses (193 nm wavelength, 15 ns time duration) were used for the experiments. Cu-Au bimetallic thin-film sample surfaces are structured under ArF excimer laser irradiation during the ablation process. Laser irradiation experiments were carried out using different laser fluences, the number of pulses, and focusing optics. Morphology of the irradiated surfaces and images of the nanostructures were obtained by the scanning electron microscopy method. Also, the optical and plasmonic behaviors of the nanostructures were collected by UV-Vis spectroscopy. Elemental composition and its spatial distribution were obtained using energy-dispersive x-ray spectroscopy (EDS) and mapping. EDS mapping shows that bimetallic nanospheres have a core-shell structure. Our results show that different laser irradiation parameters change the nanostructures’ composition, size, distribution, morphology, and optical properties. Cu-Au nanospherical structures can be used for nano-biosensing, catalysis, and enhanced spectroscopy applications.

UV laser generated micro structured black surface on commercial TiO2-containing glass

ArF excimer laser (193 nm, 20 ns) irradiation of commercially available TiO2-containing glasses in ambient air leads to a darkening of the surface and a bumpy surface micro structure. This process goes along with a phase separation between silicon-rich and titanium-rich phase near the glass surface. The black appearance can be attributed to the light scattering of the micro structured surface and absorption due to partial reduction of the titanium oxide. The process can be applied for marking the glass surface with high contrast.

Fabrication of Silicone Rubber-Based Biochip for Disinfection Under Deep-UV Light by ArF Excimer Laser-Induced Photodissociation

A silicone rubber-based biochip for disinfection under deep-UV light exposure was successfully fabricated by an ArF excimer laser. To fabricate the biochip, periodic micro-swelling structure of silicone rubber was photochemically formed by the ArF excimer laser-induced photodissociation of Si–O bonds of silicone rubber. It was found that the growth rate of the micro-swelling structure could be controlled by varying the laser pulse repetition rate; a slow growth of roughly 100 ms and longer per laser pulse was recognized. In addition, no change of each the micro-swelling height formed at various laser pulse repetition rates was also found in the range of 300–18,000 of laser pulse number. Using such the wide processing window, moreover, the periodic micro-swelling structure could be modified into photoluminescent property by long irradiation of ArF excimer laser, while maintaining the micro-swelling height. Blue photoluminescence from the modified micro-swelling structure was observed under a deep-UV light exposure. Thus, each the periodic micro-swelling structure with various desired heights could be bonded to a flat plate of fused silica glass to have equal gaps. A small amount of solution could be confined in the equal gap to disinfect virus/bacteria in the solution under deep-UV light for analytical application.

Greener hydrophilicity improvement of polypropylene membrane by ArF excimer laser treatment

The modification of chemical and physical properties of polypropylene (PP) membrane has been of interest as the creation of hydrophilic surface broadens their potential applications. Herein, we describe the use of laser surface modification methodology to overcome the hydrophobic nature of polypropylene membrane via the deployment of an ArF excimer laser. The modified samples were characterized by means of attenuated total reflectance Fourier transform infrared (ATR-FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), water contact angle (WCA) measurement, and water flux (WF) test. The results suggest that ArF excimer laser irradiation of PP membrane results in the generation of some polar functional groups and surface morphological changes both of them being effective for enhancing the hydrophilicity of PP membrane. In addition, despite increased hydrophilicity of PP membrane at higher fluences of ArF excimer laser, WF decreases due to the covering of pores by melted PP; being 100 mJ/cm2 under the optimized laser fluence.

The effect of selective mineralization of PLLA in simulated body fluid induced by ArF excimer laser irradiation: Tailored composites with potential in bone tissue engineering

In this paper we exposed samples of poly(l-lactide) (PLLA) extruded foil to ArF excimer laser (193 nm) radiation near the ablation threshold. The modified foil was immersed in the Simulated Body Fluid (SBF) at 37 °C for both short and long time (short term: up to 24 h, long term: up to four weeks). We described the physicochemical changes in PLLA before and after incubation in SBF. The laser irradiated PLLA incubated in SBF revealed turbidity on the irradiated surface. UV–Vis spectroscopy showed a remarkable decrease in transmittance for the irradiated PLLA incubated in SBF as compared to the non-irradiated PLLA incubated in SBF. Scanning electron microscopy proved the presence of minerals on the surface of PLLA in the laser irradiated area. The mineralization occurred only on the irradiated surface indicating that the process is selective. In the mineralized area a reduction of water contact angle was observed, suggesting a higher hydrophilicity of the surface. Moreover, a reduction in molecular weight was recorded in the long term incubation experiment for irradiated PLLA as compared to the unmodified sample. The samples were also investigated in terms of supramolecular changes in the material (DSC) and in terms of their thermal properties (TGA).

Comments on the 2013 ICNIRP Laser Guidelines.

Comments on the 2013 ICNIRP Laser Guidelines.

Surface defects state analysis of laser induced graphene from 4H-SiC

We demonstrate the surface defect type, density and related electrical modification of graphene sheet generated by 193-nm ArF excimer laser irradiation on n-type 4H-SiC. The charge density difference and partial density of states (PDOS) carried out by density functional theory (DFT) calculations predict the graphene with lattice imperfection can induce virtual bound states at the vacancy sites and Fermi level shift compared to perfect graphene. The surface defects density of laser generated graphene is characterized by nanoscale electrical measurements using the conductive atomic force microscope (c-AFM). The corresponding current–voltage (I–V) curves show that the electronic charge transfers, thereby electrical conductivities of laser generated graphene, are influenced by the lattice defects. The defect densities are tunable by change laser fluence and pulse number. This research provides an understanding of the interfacial transport properties between laser generated graphene and 4H-SiC through a detailed analysis of surface defects.

Laser-induced damage and periodic stripe structures of a CaF2 single crystal by an ArF excimer laser

The laser-induced damage threshold of a calcium fluoride (CaF2) single crystal was obtained by a 193 nm ArF excimer laser. The damage morphology of the crystal was analyzed. The results showed that the surface of CaF2 single crystal broke along the natural cleavage plane under ArF excimer laser irradiation, some fragments fell off, and Newton’s rings were observed on the curved fragments. Laser-induced periodic stripe structures (LIPSS) appeared on the surface layer beneath the fragments that peeled off. The spacing of LIPSS was measured, and the formation mechanism of LIPSS was analyzed based on the interference model.

Near-Infrared Luminescence of Bismuth in Silica-Based Glasses with Different Additives

The near-infrared (NIR) luminescence spectra and changes caused in them by an exposure to ArF excimer laser radiation were studied in bismuth-doped silica-based glasses containing Al, P or Ge and B additives. Experiments were conducted using specimens in the form of optical waveguides synthesized by surface plasma chemical vapor deposition (SPCVD), using bismuth-doped glass sample as the light-guiding core. Excited by ~808, ~904, and ~970 nm wavelength laser diodes, the NIR luminescence spectra were recorded in the 700–2000 nm wavelength range at temperatures of 105 and 300 K. The UV laser treatment was found to cause changes in both integrated intensity and spectrum shape of NIR luminescence associated with bismuth impurities. The observed changes are discussed with the assumption of photo-induced reconfiguring of different bismuth inclusions, which might present in the glass network in the form of separate ions and atoms, interstitial molecules, and bulk semiconductor nanoclusters.

The influence of co-doping agents on bismuth clustering in silica synthesized by SPCVD

We investigated the variation of near-infrared (NIR) luminescence spectra of bismuth-doped silica-based glasses caused by exposure to intense deep UV (193 nm wavelength) laser radiation. Bismuth-doped optical waveguides consisting of silica with additives of Al and P as the light-guiding core, synthesized via surface-plasma chemical vapour deposition (SPCVD) technology, served as the samples in our experiments. Spectra of steady-state NIR luminescence excited by 808, 904, and 970 nm wavelength laser diodes were measured in a wavelength band of 1-2 μm at temperatures of 105 and 300 K. We found that exposing the glass to intense ArF excimer laser radiation leads to NIR luminescence integral intensity and spectrum profile changes. The observed changes are discussed in the assumption that the UV laser exposure causes photoinduced rearrangement of the glass network in the vicinity of bismuth inclusions. It is expected that the latter are present in the glass network in the nature of separate ions, atoms, as well as 3D clusters.

ArF excimer laser debrides burns without destruction of viable tissue: A pilot study

IntroductionRecent evidence indicates that early removal of eschar by tangential debridement can promote healing. Laser debridement can be used for debridement of areas that prove challenging for debridement using tangential excision. In particular, irradiation with an ArF excimer laser ablates desiccated eschar and is self-terminating, preserving hydrated or viable tissue. MethodsThermal burns were created on the flanks of two outbred, female Yorkshire pigs using aluminum bars heated to 70°C and applied for different lengths of time. Three days after injury, burns were debrided using an ArF excimer laser (193nm). Tissue was harvested immediately after debridement and 7days after debridement (10days after burn). ResultsData from a pilot study demonstrates that ArF excimer laser irradiation removes burn eschar and promotes healing at 10days after burn. ArF excimer laser debridement is self-terminating and preserves underlying and adjacent perfused tissue. Potentially, this modality would be ideal for the complex curvilinear structures of the body.

Insight on agglomerates of gold nanoparticles in glass based on surface plasmon resonance spectrum: study by multi-spheres T-matrix method

The formation of a localized surface plasmon resonance (SPR) spectrum of randomly distributed gold nanoparticles in the surface layer of silicate float glass, generated and implanted by UV ArF-excimer laser irradiation of a thin gold layer sputter-coated on the glass surface, was studied by the T-matrix method, which enables particle agglomeration to be taken into account. The experimental technique used is promising for the production of submicron patterns of plasmonic nanoparticles (given by laser masks or gratings) without damage to the glass surface. Analysis of the applicability of the multi-spheres T-matrix (MSTM) method to the studied material was performed through calculations of SPR characteristics for differently arranged and structured gold nanoparticles (gold nanoparticles in solution, particles pairs, and core–shell silver–gold nanoparticles) for which either experimental data or results of the modeling by other methods are available. For the studied gold nanoparticles in glass, it was revealed that the theoretical description of their SPR spectrum requires consideration of the plasmon coupling between particles, which can be done effectively by MSTM calculations. The obtained statistical distributions over particle sizes and over interparticle distances demonstrated the saturation behavior with respect to the number of particles under consideration, which enabled us to determine the effective aggregate of particles, sufficient to form the SPR spectrum. The suggested technique for the fitting of an experimental SPR spectrum of gold nanoparticles in glass by varying the geometrical parameters of the particles aggregate in the recurring calculations of spectrum by MSTM method enabled us to determine statistical characteristics of the aggregate: the average distance between particles, average size, and size distribution of the particles. The fitting strategy of the SPR spectrum presented here can be applied to nanoparticles of any nature and in various substances, and, in principle, can be extended for particles with non-spherical shapes, like ellipsoids, rod-like and other T-matrix-solvable shapes.

Formation and implantation of gold nanoparticles by ArF-excimer laser irradiation of gold-coated float glass

To develop a technique for the production of submicron line patterns and directed arrays of plasmonic nanoparticles, the generation and implantation of gold nanoparticles into float glass surfaces was studied by means of ArF-excimer laser irradiation (193 nm) below the ablation threshold of the glass which was sputter coated with a gold layer with a thickness of 70 nm. The formation of gold particles was confirmed by the characteristic surface plasmon resonance (SPR) peak at ∼550 nm. The intensity of the SPR peak of gold particles embedded in the glass matrix increases with the number of applied laser pulses, indicating a different degree of implantation of the gold nanoparticles into the glass surface. It was revealed that the laser implantation of the generated gold particles into the glass is supported on the tin-bath side by the enhanced absorption of tin ions. The dependences of SPR parameters upon the number of laser pulses at different fluences were obtained. Using the methods of X-ray diffraction and extended X-ray absorption fine structure, the mean size of implanted gold particles was estimated at 15–20 nm. This particle size was confirmed by analytical (scanning) transmission electron microscopy, but a small fraction of single particles with a size of ∼50 nm have also been observed. The particles arrangement was further examined by the fitting of experimental optical extinction spectra, varying the particles sizes and interparticle distances within the direct calculations of spectra by the multi-spheres T-matrix method, considering the possible agglomerations of particles. The applied experimental technique provides the creation of arrays of gold nanoparticles in the near-surface region of the glass, which can be used as the substrates or nuclei in the glass for producing bimetallic nanoparticles with gold as the core and SPR characteristics varied in a wide range of visual wavelengths.

Efficiency of Bragg grating inscription by ArF excimer laser radiation depending on orientation of birefrin-gence axis of anisotropic optical fiber

Efficiency of Bragg grating inscription by ArF excimer laser radiation depending on orientation of birefrin-gence axis of anisotropic optical fiber

Nano-carbon pixels array for ionizing particles monitoring

The paper deals on the response of a polycrystalline diamond sensor, 500μm thick, to particles from a 90Sr β-source. 21×21 nano-carbon pads, with 0.18mm×0.18mm area each, were realized by ArF excimer laser irradiation on one diamond face, whereas a 7×7mm2 backside contact was fabricated and used for sensor biasing during characterization of sensor under β-source irradiation. The carbon pads embrace a number of grains, which show different degrees of surface graphitization dependent on the grain orientations. Each carbon pad exhibits a linear I(V) response up to 200V. The average number of charge carriers collected by a single pixel, as well as the distribution of pixels involved by the impinging particle tracking, is analyzed as a function of the applied voltage recording the signals acquired by 16 pixels at a time. The pulse height distribution is not affected by reversing the bias polarity. For a single pixel, the most probable collected charge value is 1.40±0.02fC whereas the mean value gives 〈Q〉coll=1.67±0.02fC (10,430±120 electrons). The charge collection distance was measured taking into account the effect induced by high-energy electrons and found to be 285±3μm, demonstrating the absence of bulk defects induced by the laser graphitization processing. Cross-talk effects between nearest-neighbor pixels have been excluded analyzing the results obtained in a batch of more than 1000 events even if the same cannot be excluded under higher energy particles.

One-pot synthesis and transfer of PMMA/Ag photonic nanocomposites by pulsed laser deposition

Nanocomposite films comprising metallic nanoparticles in polymer matrices find increasing use in emerging photonic, electronic and microsystem applications owing to their tailored advanced functionalities. The versatile development of such films based on poly-methyl-methacrylate (PMMA) matrix having embedded Ag nanoparticles is addressed here. Two low-cost one-pot chemical methods for the synthesis of bulk target nanocomposite materials are demonstrated. These nanocomposites are subsequently transferred via pulsed laser deposition using 193 nm ArF excimer laser radiation, producing films maintaining the structural and functional properties. Both target- and laser-deposited materials have been thoroughly characterized using microscopic, spectroscopic and thermal analysis methods. Infrared spectra demonstrated the close molecular PMMA chain similarity for both target and film materials, though structural alterations identified by thermal analysis proved the enhanced characteristics of films grown. High-resolution electron microscopy proved the transfer of Ag nanoparticles sized 10–50 nm. Visible absorption peaked in the spectral range of 430–440 nm and attributed to the Ag nanocomposite plasmonic response verifying the transfer of the functional performance from target to film.

Fascinating Diazirinone: A Violet Gas

AbstractDiazirinone (cyclic N2CO) recently identified in solid noble gas matrices and in the gas phase by infrared spectroscopy, has now been trapped at –196 °C as a neat brownish‐yellow solid, and characterized by low‐temperature IR and Raman spectroscopy. Evaporation of the solid yields violet gaseous N2CO, which is surprisingly stable in a clean quartz cell. Its decay at room temperature in the dark follows a second‐order rate law (k2 = 4.9 × 10–2 L mol–1 s–1) with a half‐life of 30 h at an initial pressure of 5 mbar. The visible absorption spectrum of the gas reveals a structured band with the 0–0 transition at 567 nm (17651 cm–1), and its assignment has been made with the aid of theoretical calculations. Cyclic diazirinone that is isolated in solid Ar at 16 K decomposes upon visible light irradiation to yield N2 and CO, but after being exposed to ArF excimer laser irradiation (193 nm) the N=N bond is cleaved and the open‐chain isomers NOCN, ONCN, and ONNC are formed.

ChemInform Abstract: Elusive Fluoro Sulfinyl Nitrite, FS(O)NO, Produced by Photolysis of Matrix‐Isolated FS(O)2N.

AbstractTriplet fluoro sulfonyl nitrene, FS(O)2N is generated by ArF excimer laser irradiation (λ = 193 nm) of FS(O)2N3 isolated in solid noble gas matrices.

Self-organized Nano-cone Arrays in InP/InGaAs/InGaAsP Microstructures by Irradiation with ArF and KrF Excimer Lasers

We discuss the effect of ArF (laser=193 nm) and KrF (laser=248 nm) excimer laser irradiation of InP/InGaAs/InGaAsP quantum well (QW) microstructures on surface morphology of the top InP layer. The irradiation was carried out in air with lasers delivering up to 700 pulses of fluence from 82 to 142 mJ/cm 2 . We observe the formation of nano-cone structures having their period increasing from 450 to 1080 nm for KrF laser, and from 675 to 875 nm for ArF laser, in proportion to the laser fluence and pulse number. The chemical and structural modification of the laser irradiated surface has resulted in the enhancement of the QW photoluminescence emission up to 1.4 times when compared to the non-processed material. Thus, the excimer laser processing of the surface of InP capped InGaAs/InGaAsP QW microstructures using relatively low pulse fluence, has been found attractive for the fabrication of enhanced optical emission semiconductor devices.

Laser induced surface modification of polylactide

The modification induced in polylactide (PLA) by the ArF excimer laser radiation has been investigated. Various fluences and numbers of laser pulses were applied to modify surface properties. The contact angles of test liquids (water and diiodomethane) were measured with use of a goniometer while the surface energy (SE) was calculated by the Owens–Wendt method. Changes in the chemical composition of the PLA surface layer were studied using the X-ray photoelectron spectroscopy (XPS). Analysis of the morphological changes in the polymer surface layer was performed via the atomic force microscopy (AFM). It was found that the surface energy change was affected by surface oxidation as well as by surface roughness resulted from laser irradiation. The influence of laser induced surface oxidation and roughness on SE depended on applied fluence and the number of laser pulses.