激光诱导Al等离子体吸收谱分析

用Nd:YAG脉冲激光烧蚀金属Al靶获得等离子体，激光脉冲能量为115mJ.pulse^-1，用氮气作保护气体，压强为1个大气压，获得激光诱导Al等离子体的时间分辨谱。分析了Al等离子体辐射特征。根据连续辐射时间分布，对吸收谱的形成作了简单的解释，认为Al原子对连续辐射的共振中收是形成吸收谱中的“凹谷”的主要机制。

Analysis of Absorption Spectra of the Plasma Induced by Laser Ablating Al

The plasma was obtained with pulsed Nd:YAG laser beam ablating Al target.The energy of a pulsed laser was set up to 115 mJ,N 2 was used as protecting gas at the pressure of one atmosphere.With the time resolved technology,the time resolved spectra of Al plasma radiation were acquired,and its characteristics were analyzed.According to the profiles of continuous radiation at different time,the structures and evolutions of absorption spectra were briefly discussed.We suggested that the resonance absorption of continuous radiation by Al atom was the main mechanism.When N 2 was used as protecting gas,continuum radiation was added an absorbed spectrum on almost every time resolved spectrum.The bottoms of absorbed spectra located about 390 0 nm.The absorbed spectra inclined to short wavelength.With delayed time increasing,the absorbed spectra were broadened and extended to continuum radiation,but the bottoms kept at about 390 0 nm and inclined more to short wavelength.These phenomena were much consistent with those that occurred using Ar as protecting gas.So it is suggested that the absorbed spectra have nothing to do with ambient gas,and that they mainly derive from the absorption of continuum radiation of the plasma by aluminum atoms.