Effects Of Excimer Laser Irradiation Research Articles

Excimer Laser Beam Interaction with Sintered Y2O3- Doped Aluminium Nitride Ceramic: Fundamentals and Appplication

ABSTRACTSintered aluminium nitride ceramic is most attractive for applications in modern electronic packaging, due to its high thermal conductivity and its high electrical resistivity. Among the sintering additives which are mentioned in the literature, Y2O3 is used most often as sintering accelerator and densificator for AlN commercial ceramics.Since excimer lasers have recently proved to be efficient in ceramic processing for industry, the effects of excimer laser irradiation on sintered Y2O3;rdoped AlN ceramic have been studied in this work. Raman spectroscopy, low-angle X-ray diffraction and scanning electron microscopy equipped with energy-dispersive X-ray analysis are used for characterizing both the initial and processed materials. The results reveal that yttrium-containing phases which are present at the AlN grain boundaries play an essential role in coupling the (λ =248nm) excimer laser beam with sintered material. Moreover, the laser-induced decomposition of these pre-existing complex phases and the subsequent spinel-like formation upon autocatalytic copper (or nickel) deposition are associated with (and explain) the excellent adhesion of the so-formed metal layer onto the ceramic substrate.

Characterization of Si<sub>3</sub>N<sub>4</sub> Surface after Excimer Laser Radiation

The effect of excimer laser radiation to silicon nitride ceramic surface morphology was investigated. The response of the surface at irradiation to different laser fluences and in-vacuo measurements of the particle emission due to laser irradiation were examined. The irradiated surface showed pillar-like features at low fluence (20kJ/m2), however, flat surfaces were produced at high fluence (100kJ/m2). Quadrupole mass spectrometry during laser irradiation showed that the emitted particles were Si+, Y+, O and N. It is thought that the surface silicon nitride and/or grain boundary crystal phase (Si3N4⋅Y2O3) was decomposed during laser irradiation, and the resulting Si+ to form SiO2 layers and/or pillars on the surface. These surface features degrated the strength of the specimens due to pore formation just under the surface.

An in vivo study of the effect of excimer laser irradiation on degenerate rabbit articular cartilage

Eighteen adult rabbits with mechanically induced degenerative arthritis of one knee were divided into two groups. The first group underwent arthrotomy and lavage of the arthritic joint. The second group underwent arthrotomy and irradiation of the degenerate articular surface with the Excimer (xenon chloride ultraviolet, 308-nm) laser (Arthrex Arthrolase MAX-10, Germany) in a saline environment. Rabbits from each group were killed at intervals up to 12 weeks for histological and metabolic studies of their articular cartilage. In the control group there was no improvement in the macroscopic or microscopic appearance of the articular surface. In the laser-irradiated group initially there was macroscopic and microscopic smoothing of the fibrillated surface. By 6 weeks the surface had begun to show the reappearance of fibrillation. There was no evidence that there was any increase or decrease in mitotic or metabolic activity in the laser-irradiated group as compared with the controls.

Treatment of metal surfaces with excimer laser radiation for radiative applications

In this study the effects of intense excimer laser irradiation (10(8)-10(9) W cm(-2)) on some radiative properties of copper, aluminum, magnesium, tantalum, and molybdenum are investigated. The short pulse duration of the excimer laser (30 ns FWHM) and the wavelength of the radiation initiate a processing regime that is dominated by the effects of a laser-supported plasma above the workpiece surface. A laser-supported detonation wave is observed that acts on a thin molten surface layer. The resultant structure that is frozen on the surface is dependent on the thermophysical properties of the metal and the number and manner in which multiple pulses are applied to the surface. This surface roughness has features on both the macro- and microscopic scale that affect the radiative properties of the surface. The surface plasma also initiates very fast reaction rates that can create a thick oxidized layer on the metal surface. The surface oxide layer may either be lightly (CuO particles on a copper substrate) or tightly adhered (Al(2)O(3) on aluminum) to the surface. The effect of excimer laser irradiation is characterized with scanning electron microscopy and Fourier transform infrared spectroscopy. Data on solar absorptivity α(s), spectral reflectivity ρ'(λ), bidirectional reflectivity ρ″(λ), and total near-normal total emissivity ε'(T) are also presented that show that in some cases heavily irradiated samples simulate the radiative behavior of a flat absorber.

Photoluminescence and Its Excimer Laser Irradiation Effects in SiO2 Film Prepared by Photo-Induced Chemical Vapor Deposition

Defects and other imperfections in photo-induced chemical vapor deposition (photo-CVD) SiO2 films have been characterized by photoluminescence excited by ArF and F2 excimer lasers. Photoluminescence peaks have been observed at around 2.7, 3.5 and 4.4 eV and are characteristic of both the deposition temperatures of photo-CVD and excitation energy. The intensity of the photoluminescence peak at around 2.7 eV initially increases with ArF excimer laser irradiation but decreases after about 2000 shots. On the other hand, it decreases monotonously with F2 excimer laser irradiation. The origins of these peaks have been discussed in terms of various dependences of photoluminescence and absorption spectra.

Abstract #52 — Effect of excimer laser irradiation on human pulpal fibroblasts

Abstract #52 — Effect of excimer laser irradiation on human pulpal fibroblasts

Diamond device delineation via excimer laser patterning

Excimer lasers are high peak power gas lasers, commonly operating in the UV region of the electromagnetic spectrum, i.e. between 157 and 351 nm. They have been extensively applied to patterning and machining of high performance materials, such as polymers and fibre-reinforced composites. The use of high power, UV excimer lasers offers an alternative route for structure delineation in electronic device fabrication, by providing a resist-free, patterned processing capability. This is in contrast to conventional etching processes, such as wet chemical, reactive ion or plasma-assisted methods. The effect of excimer laser radiation on chemical-vapour-deposited diamond has been studied to find the optimum conditions for device patterning. The effect of chemical-vapour-deposited diamond film quality (amount of sp 3-bonded carbon) on the etch rates and laser processing parameters (power, pulse rate and wavelength) also have been examined. A tentative mechanism for the ablation of diamond has been proposed.

Ca, Pを含む生体組織のエキシマレーザー照射効果

Ca, Pを含む生体組織のエキシマレーザー照射効果

Excimer laser irradiation effects on ethylene-tetrafluoroethylene copolymer.

Excimer laser irradiation effects on ethylene-tetrafluoroethylene copolymer.

Biological effects of excimer laser radiation

Excimer laser radiation at 193 nm (ArF) and 308 nm (XeCl) is being used for medical applications. Because ultraviolet radiation is absorbed by DNA and causes cell killing, mutagenesis, and carcinogenesis, the effects of 193- and 308-nm excimer laser radiation on biological material have been studied. Radiation at 193 nm causes less cell killing than conventional 254 nm germicidal light per incident photon. Radiation at 193 nm showed very low potential for causing mutation because proteins absorb strongly at 193 nm, thereby reducing the photon flux reaching the nuclear DNA. In addition, the quantum yield of a cytotoxic and mutagenic photoproduct of DNA is lower for 193 nm than for 254 nm. Radiation at 308 nm is cytotoxic and mutagenic. Results of in vitro assays indicate that the relative ability of excimer laser radiation to cause DNA damage decreases in the order 248 nm>308 nm>193 nm. >

Excimer laser irradiation effects on fluoropolymer and aromatic polymer.

Excimer laser irradiation effects on fluoropolymer and aromatic polymer.

Laser-induced geometrical change of fluorescent traps in cast films of carbazole-containing bilayer membranes

The effect of excimer laser irradiation on cast films of carbazole-containing bilayer membranes was investigated by measuring absorption and fluorescence spectra. A remarkable fluorescence spectral change on laser irradiation was observed, although no absorption spectral change was ever observed. The fluorescence spectral change was different from that induced by xenon lamp irradiation, and was attributed to structural change of the carbazolyl aggregates induced by a thermalization process from higher excited states.

Irradiation effects of excimer laser radiation and electron beam on polypropylene and ethylene-tetrafluoroethylene copolymer films

The irradiation effects of the intense ultraviolet radiation from an excimer laser on polypropylene (PP) and ethylene-tetrafluoroethylene (ETFE) copolymer films are compared with those from electron beam studies. Irradiation of PP films with a KrF laser and an electron beam induced the degradation of the polymer, and use of an ArF laser selectively decomposed the alkyl phenol type additive contained as an antioxidant in PP instead of degrading the polymer. Irradiation with a KrF laser induced the carbonization of ETFE copolymer due to polymer degradation, and irradiation with an ArF laser and an electron beam formed CO and CC groups in the polymer chains.

Effects of excimer laser irradiation on the transmission, index of refraction, and density of ultraviolet grade fused silica

Radiation-induced changes in high-purity fused silica during prolonged irradiation with a pulsed laser at 193 nm have been studied. Radiolytically induced UV absorption bands, an increase in index of refraction, and stress birefringence are observed. The formation mechanisms are analyzed in terms of radiolytic atomic rearrangement of a-SiO2 initiated by two-photon absorption. The quantum efficiency for the formation of E′ point defects per pair of absorbed 193 nm photons has been determined to be ∼7.5×10−4; matrix compaction, as high as a few parts in 10−5, is identified as the source of the birefringence and index change. It has been further observed that E′ centers can be photobleached.

エキシマレーザーの血液に対する影響

We examined effects of excimer laser irradiation on blood. Five vials, each of which contained 3ml of blood, were exposed to 37.5mJ laser beam at 10 PPS in repetition rate for 10, 20, 30, 40, 50 seconds. One vial was left untreated as a control. No change in hematocrit value was observed after excimer laser irradiation. In contrast, the level of plasma free hemoglobin rose progressively with each increased duration of exposure. This study indicates that the lysis of erythrocytes does not occur in the laser-exposed cells. However, the damage to erythrocyte membrane took place as it was evidenced by progressive hemoglobin leakage into plasma.

Effects of Excimer Laser Irradiation on Mbe and Mo-Mbe Growth of (Al)Gaas On Gaas And (Ca,Sr)F2/Gaas Substrates

ABSTRACTWe report the growth of GaAs by laser-assisted molecular beam epitaxy, using As4 and either elemental Ga or triethylgallium (TEG) sources, and a 193 nm ArF excimer laser. Laser irradiation of (Al)GaAs has no effect on the growth rate or Ga-to-Al incorporation, when GaAs substrates and elemental group-III sources are used. When GaAs is grown from TEG, laser irradiation results in a selective-area film growth at temperatures below 450°C, where growth due to pyrolytic decomposition of TEG is very slow. The process is extremely efficient, with roughly unit probability for impinging TEG molecules sticking and being dissociated by laser radiation to form GaAs. From the strong dependence on laser fluence, the growth enhancement process appears to be pyrolytic in nature (due to rapid transient healing by the pulsed laser), and not photolytic. The cross section for photolysis must be at least ten times lower than the gas-phase value (9x10-18cm2). Using either Ga source, laser irradiation improves surface morphology and photoluminescence yields, compared to areas receiving less intense laser radiation.In growth of GaAs from elemental sources on (Ca, Sr)F2 lattice-matched to GaAs, laser irradiation inhibits growth due to laser-induced thermal desorption of adsorbed Ga atoms, which are relatively weakly bound to (Ca,Sr)F2 compared to GaAs surfaces.