308nm准分子激光对C60薄膜的刻蚀特性研究

测量在空气和真空中３０８ｎｍ准分子激光对Ｃ６０薄膜的刻蚀速率和刻蚀阈值，讨论了环境中氧气对刻蚀特性的影响。     

C60薄膜的准分子激光刻蚀及形貌分析

报道了准分子ＸｅＣｌ（３０８ｎｍ）紫外激光刻蚀Ｃ６０膜的实验研究及对刻蚀薄膜的形貌分析。基于形貌分析的结果提出其刻蚀机理。     

XeCl激光泵浦S2分子获得紫外激光振荡

本文报道利用ＸｅＣｌ准分子激光（３０８．１ｎｍ）横向泵浦硫双原子分子激光器，在近紫外谱区（３３０．９～３９０．０ｎｍ）的六条谱带上获得激光振荡。计算并测量了Ｓ２分子的吸收系数及小信号增益系数，从而确定了最佳泵浦波长。     

纯石英光纤的高功率紫外激光传输特性

报道了几种国产阶跃型纯石英光在传输ＸｅＣｌ（３０８ｎｍ）准分子激光时的损耗特性及其破坏阈值的实验研究结果，同时也报道了这些光纤的弯曲损耗和弯曲断裂特性，结果表明，这些紫外级石英光纤，最小的透过损耗约为０．３３ｄＢ／ｍ，表面破坏阈值约为１０Ｊ／ｃｍ＾２。     

XeCl（308nm）脉冲准分子激光淀积类金刚石薄膜

利用ＸｅＣｌ（３０８ｎｍ）脉冲准分子激光淀积技术在功率密度５×１０８Ｗ／ｃｍ２、室温、真空度１０－３Ｐａ的条件下，制备出不含氢成分的类金刚石薄膜，研究了类金刚石薄膜的特性及其随制备工艺条件的变化规律。研究了激光诱导的碳等离子体发射光谱，探讨了类金刚石薄膜的形成机理。     

308nm处气体的拉曼微分散射截面值

采用Ｐｌａｃｚｅｋ模型，选取部分可用作拉曼介的气体在４８８ｎｍ处的拉曼微分散射截面作为基准，外推得出３０８ｎｍ处的散射截面，通过将结果与Ｈ２几个已有实验结果的比较及讨论，分析了推算结果的可靠性，为ＸｅＣｌ准分子激光拉曼散射实验提供分析的基础参量。     

准分子激光作用下二氧化钛的表面变性

适当能量密度的准分子激光作用于二氧化钛时，电导性能发生了显著的变化，室温下从原来的绝缘体转变为半导体，同时表面颜色也发生了变化．利用X射线衍射、X射线光电子能谱及显微分析等多种测试方法进行了分析、比较，确定了该过程是由于短脉冲的准分子激光作用，造成了二氧化钛的快速升温熔化和快速冷凝重构，导致氧的缺位，引起了化学配比偏离．用热传导方程对能量密度阈值进行了近似估算，结果与实验基本相符 关键词：     

可调谐淬灭式染料激光器研究

研究了可调谐淬灭式染料激光器的染料浓度和泵浦能量对淬灭效果的影响，并且研究了它的调谐范围。对于３０８ｎｍＸｅＣｌ准分子激光泵浦淬灭式香豆素４９８染料激光器，得到了一些具体的参数。     

蓝光波段染料Coumarin461掺杂的凝胶材料的光学性质

采用溶胶－凝胶技术合成了掺杂蓝光段激光染料Ｃｏｕｍａｒｉｎ４６１的ＳｉＯ２基固体材料，用波长为３０８ｎｍ的Ｘｅｃｌ激光器做泵浦源，横向泵浦，获得了峰值波长为４６５ｎｍ的蓝光波段激光输出，在泵浦光强度为１０ｍＪ时激光输出达到０．５３ｍＪ，转换效率为５．３％。     

实时测量308nm激光泽薄膜的损伤阈值

用菜射光法，建立了一套实时监视与测量３０８ｎｍ激光对全的帮增透膜的损伤的实验装置。实时观察到了损伤从起始、加深直至饱和的整个过程的波形，用这一装置测量了全反膜和增透膜在３０８ｎｍ激光作用一的损伤阈值，测得是全反膜在０°与４５°入射角时的损伤阈值分别为１．７与１．０Ｊ／ｃｍ＾２。而增秀原阈值为１．３Ｊ／ｃｍ＾２。     

用于薄膜沉积的XeCl激基激光器研制

以镀制半导体薄膜、巨磁薄膜、金刚石及其它薄膜,外延生长及后续的光刻,激光与物质的相互作用、等离子体研究为目的,设计、研制了脉冲放电激励的XeCl激基激光器.试验结果表明:激光脉宽18ns,单脉冲能量150mJ,矩形光斑大小2cm×1cm,束散角3mrad,最高重复频率5HZ.与同类激光器相比,具有结构简单、造价低廉、性能稳定等特点.     

Formation of periodic structures by surface treatments of polyamide fiber: Part I. UV excimer laser irradiation

The processes of UV excimer laser irradiation (both high- and low-fluence) of polyamide fiber were systemically studied, including the surface temperature of the material during the treatment and possible mechanisms for the structure formation. The fluence applied in the high-fluence laser irradiation was above the ablation threshold of the material. The ablation of polymer can be described on the basis of photo-thermal bond breaking within the bulk material. The fluence applied in the low-fluence laser irradiation was far below the ablation threshold of the material. The development of low-fluence laser-induced structures is closely related to the absorption coefficient of the material, the laser fluence used, the polarization of the laser beam, the angle of incidence, and the number of laser pulses applied.     

准分子激光取样与电感耦合等离子体质谱和光谱联用分析仪器研究进展

将准分子激光剥蚀取样后的产物经由电感耦合等离子质谱与光谱分析,从而获得被激光剥蚀样品的元素与同位素含量信息,是迄今为止适应于表面原位微区分析最为重要的分析科学技术手段之一。基于准分子激光剥蚀取样技术分别与电感耦合等离子体质谱或发射光谱技术联用的分析手段, 已经被广泛应用于地质学、材料学、环境科学,甚至生命科学领域的原位微区分析研究当中, 并且分别体现了各自技术的优势：固体材料表面的原位微区激光剥蚀取样技术既可以获取被分析材料的原位微区信息（满足了需要空间高分辨的微区元素与同位素信息提取的需求）,又避免了样品预处理带来的可能污染问题,同时,脉冲宽度为纳秒或飞秒的深紫外准分子激光具有极高的能量密度,用于剥蚀固体材料表面取样产生的热效应较低,引起的化学元素和同位素分馏效应不明显,其剥蚀取样的产物（气溶胶）可以更为接近代表原被剥蚀固体材料表面的化学元素和同位素组成;电感耦合等离子质谱分析和光谱分析技术已被证明可以高质量地提供被分析样品的元素与同位素信息,激光剥蚀取样技术与电感耦合等离子体质谱分析技术联用已经为固体材料表面的原位微区元素和同位素分析,带来了大量可信的科学分析数据,近年来将质谱分析手段与光谱分析手段联用于等离子体分析,并应用于元素和同位素化学分析,利用质谱分析与光谱分析方法各自的优点,优势互补,旨在提高电感耦合等离子质谱和光谱技术的元素和同位素分析精度,有望成为了一种新的分析科学方案。从应用于原位微区微量元素与同位素化学分析的需求出发,介绍了基于准分子激光剥蚀取样技术和电感耦合等离子体质谱与光谱分析技术同步联用的分析技术方案,并对于研发相关分析仪器的进展进行了概括与展望。     

Pulsed laser ablation of La0.5Sr0.5CoO3

The ablation process of La_0.5Sr_0.5CoO₃ by a spatial uniform 248 nm excimer laser beam has been characterized. Ablation rates, changes in the target surface morphology and composition have been studied as a function of the laser fluence. The dependence of the ablation rate on the laser fluence has been explained by a model based on plasma absorption. The threshold fluence for complete dissociation of the surface has been determined and is found equal to 0.7 J/cm². Above this threshold, a steady-state target surface condition is obtained within 30 pulses. Below the threshold fluence, CoO nuclei form, which have a pronounced effect on the target composition and morphology. In addition, ellipsometric and reflectance spectra have been measured in the photon energy range of 1.8 to 5.0 eV.     

Evaluation of excimer laser ablation of thin Cr film on glass substrate by analysing acoustic emission

Excimer laser ablation of a thin Cr film on a glass substrate was evaluated through detecting acoustic emission arising from the ablation process and observing surface morphology. In the experiment, an acoustic emission transducer was coupled to the sample to acquire acoustic emissions of laser–material interaction and an oscilloscope was used to record the signals. The patterned areas were examined by using an optical microscope. Characteristics of the acoustic emissions were studied through applying a range of signal analysis tools. Several features (e.g., average power, RMS) showed a clear linkage with the ablation mechanism of thin Cr film when varying the fluence of the laser source. Moreover, the damage to the glass substrate was well discriminated by the extracted features. In sum, evaluation of acoustic emissions not only provided a tool to study the ablation mechanisms of the thin metal film but also addressed a monitoring strategy for excimer laser micromachining.     

Fabrication of high-aspect-ratio microstructures using excimer laser

An excimer laser micromachining system is developed to study the ablation of high-aspect-ratio microstructures. The study examines the ablation efficiency, specifically, the impact of changing major laser operating parameters on the resulting microstructural shapes and morphology. The study focuses on glass, although results on silicon and aluminum are also included for comparison. In ablating grooved structures, the ablation depth has been observed to be linearly proportional to the operating parameters, such as the pulse number and fluence. The results specifically indicate that ablation at low fluence and high repetition rates tends to form a V-shaped cross-section or profile, while a U-shaped profile can be obtained at high fluence and low repetition rate. The ablation rate or ablated volume has then been quantified based on the ablation depth measured and the ablated profile observed. The threshold fluence has also been obtained by extrapolating experimental data of ablation rate. The extrapolation accuracy has been established by the good agreement between the extrapolated value and the one predicted by Beer's law. Moreover, a one-dimensional analytical solution has been adopted to predict the ablated volume so as to compare with the experimental data. The reasonable agreement between the two indicates that a simple analytical solution can be used for guiding or controlling further laser operations in ablating glass structures. Finally, the experimental results have shown that increasing the repetition rate favors the morphology of ablated surfaces, though the effect of repetition rate on ablation depth is insignificant.     

Study of Nanocrystalline Diamond Film Deposited Rapidly by 500 W Excimer Laser

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Study of Nanocrystalline Diamond Film Deposited Rapidly by 500 W Excimer Laser

High quality nanocrystalline diamond film deposited rapidly by an XeCl excimer laser operated at high laser power (500 W) and repetition rate (300～500 Hz) is presented. A high deposition rate, 250 nm/thousand pulses, was obtained. The effects of laser energy fluence and repetition rate on the deposition of diamond film were investigated.     

Influence of laser fluence and irradiation timing of F2 laser on ablation properties of fused silica in F2-KrF excimer laser multi-wavelength excitation process

A collinear irradiation system of F₂ and KrF excimer lasers for high-quality and high-efficiency ablation of hard materials by the F₂ and KrF excimer lasers’ multi-wavelength excitation process has been developed. This system achieves well-defined micropatterning of fused silica with little thermal influence and little debris deposition. In addition, the dependence of ablation rate on various conditions such as laser fluence, irradiation timing of each laser beam, and pulse number is examined to investigate the role of the F₂ laser in this process. The multi-wavelength excitation effect is strongly affected by the irradiation timing, and an extremely high ablation rate of over 30 nm/pulse is obtained between -10 ns and 10 ns of the delay time of F₂ laser irradiation. The KrF excimer laser ablation threshold decreases and its effective absorption coefficient increases with increasing F₂ laser fluence. Moreover, the ablation rate shows a linear increase with the logarithm of KrF excimer laser fluence when the F₂ laser is simultaneously irradiated, while single KrF excimer laser ablation shows a nonlinear increase. The ablation mechanism is discussed based on these results. Received: 16 July 2001 / Accepted: 27 July 2001 / Published online: 2 October 2001     

Effect of spot size on cone formation in a XeCl laser ablation of polyethersulfone films

Radiation from the UV excimer lasers, with the fluence above the ablation threshold, can etch the polymer surfaces by photoablation. In some cases different microstructures may appear on the surface during the laser ablation. In this paper the effect of the laser spot size on the cone formation on polyethersulfone films has been investigated. The experiments have been performed with a XeCl laser at the wavelength of 308 nm and at the fluences of 70 and 100 mJ/cm² at air. For the investigation of the effect of the laser spot size on cone formation, the samples were irradiated at two different laser spot sizes of w₁ and w₂ = 0.1 w₁. The morphology of the processed surface was studied by scanning electron microscopy (SEM). It has shown that the shape, size and density of cones change with the change of the laser spot size. Also, the number of pulses and the pulse repetition rate which are needed for threshold of cone formation are affected by the laser beam spot size on the surface.