Optical Breakdown in Gases Induced by High-power IR CO2 Laser Pulses
Optical Breakdown in Gases Induced by High-power IR CO2 Laser Pulses
复制标题
高功率红外 CO2 激光脉冲引起的气体光学击穿
DOI：
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
J. Poyato
中科院分区：
文献类型：
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作者：
J. J. Camacho;Luis Díaz Sol;M. Santos;L. Juan;J. Poyato
本章回顾了激光诱导击穿光谱（LIBS）的一些基础知识，并介绍了我们实验室对氮气、氧气和空气等气体进行的一些实验研究。利用高功率横向激发大气（TEA） CO2激光器（λ=9.621和10.591 μm, tFWHM=64 ns，不同激光功率密度），在紫外-可见-近红外（UV-Vis-NIR）光谱范围内激发这些气体在不同压力下的LIBS。产生的等离子体的光谱以强原子、离子和分子带的发射为主。用原子线和离子线估计激发温度。电子数密度由若干离子谱线的Stark展宽得到。研究了不同物质的光谱发射强度随气体压力和激光辐照度的变化规律。实验测量了不同气体中的光击穿阈值强度。分析了导致激光击穿气体的物理过程。利用时间分辨光学发射光谱（OES）技术，在N、O和C的发射谱线上对空气LIBS中的等离子体特性进行了详细的研究。结果表明，连续谱和离子谱的衰减速度快于中性原子和分子谱。利用飞行时间（TOF） OES测量得到了不同树种的速度和动能分布。通过分析激光脉冲入射不同时刻的光谱数据，估计了激光诱导等离子体的激发温度和电子密度。利用电子密度的时间演化来估计三体复合速率常数。
This chapter reviews some fundamentals of laser-induced breakdown spectroscopy (LIBS) and describes some experimental studies developed in our laboratory on gases such as nitrogen, oxygen and air. LIBS of these gases at different pressures, in the spectral range ultraviolet-visiblenear infrared (UV-Vis-NIR), was excited by using a high-power transverse excitation atmospheric (TEA) CO2 laser (λ=9.621 and 10.591 μm; tFWHM=64 ns; and different laser power densities). The spectra of the generated plasmas are dominated by emission of strong atomic, ionic species and molecular bands. Excitation temperatures were estimated by means of atomic and ionic lines. Electron number densities were deduced from the Stark broadening of several ionic lines. The characteristics of the spectral emission intensities from different species have been investigated as functions of the gas pressure and laser irradiance. Optical breakdown threshold intensities in different gases have been measured experimentally. The physical processes leading to laserinduced breakdown of the gases have been analyzed. Plasma characteristics in LIBS of air were examined in detail on the emission lines of N, O and C by means of time-resolved opticalemission spectroscopy (OES) technique. The results show a faster decay of continuum and ionic spectral species than of neutral atomic and molecular ones. The velocity and kinetic energy distributions for different species were obtained from time-of-flight (TOF) OES measurements. Excitation temperature and electron density in the laser-induced plasma were estimated from the analysis of spectral data at various times from the laser pulse incidence. Temporal evolution of electron density has been used for the estimation of the three-body recombination rate constant.
DOI：
10.1007/978-3-642-61247-3
发表时间：
1991-10
期刊：
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影响因子：
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作者：
Iu. P. Raizer
通讯作者：
Iu. P. Raizer