Löbe Andrea, Vrenegor Jens, Fleige Rüdiger, Sturm Volker, Noll Reinhard
Fraunhofer-Institut für Lasertechnik, Steinbachstrasse 15, 52074, Aachen, Germany.
Anal Bioanal Chem. 2006 May;385(2):326-32. doi: 10.1007/s00216-006-0359-8. Epub 2006 Mar 17.
The sensitivity of laser-induced breakdown spectroscopy of solid samples depends on the number of ablated and excited analytes. Laser ablation of solid samples can be enhanced by using collinear multiple laser pulses, for example double or triple pulses, rather than single laser pulses with the same total laser pulse energy. The ablation rates and the plasma conditions are affected by the ambient gas. In this study laser ablation was examined by varying the interpulse separation of the multiple pulses, within double and triple-pulse bursts, and the gas mass density at constant gas pressure. Different ambient gases and gas mixtures consisting of argon, oxygen, and nitrogen were used to study their effect on ablation rates. In a pure argon atmosphere (99.999% v/v Ar) the ablation burst number required to penetrate a steel plate of thickness 100 microm is reduced by a factor of approximately six by use of triple-pulse bursts with a symmetric interpulse separation of 15 micros rather than single pulses with the same total burst energy of 105 mJ. For double and single pulses the factors are 1.6 for Ar and 2.8 for synthetic air. Analyte lines are 4 to 8 times more intense if an argon atmosphere, rather than air, is used.
固体样品激光诱导击穿光谱的灵敏度取决于被烧蚀和激发的分析物数量。通过使用共线多激光脉冲，例如双脉冲或三脉冲，而非具有相同总激光脉冲能量的单激光脉冲，可以增强固体样品的激光烧蚀。烧蚀速率和等离子体条件受环境气体影响。在本研究中，通过改变双脉冲和三脉冲序列中多脉冲的脉冲间隔以及在恒定气压下的气体质量密度来研究激光烧蚀。使用由氩气、氧气和氮气组成的不同环境气体和气体混合物来研究它们对烧蚀速率的影响。在纯氩气气氛（99.999% v/v Ar）中，使用具有15微秒对称脉冲间隔的三脉冲序列而非具有相同总脉冲能量105 mJ的单脉冲时，穿透厚度为100微米的钢板所需的烧蚀脉冲次数减少了约六倍。对于双脉冲和单脉冲，氩气的倍数为1.6，合成空气的倍数为2.8。如果使用氩气气氛而非空气，分析物谱线强度会增强4至8倍。
