High-resolution spectroscopy of laser ablation plumes using laser-induced fluorescence
High-resolution spectroscopy of laser ablation plumes using laser-induced fluorescence
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DOI：
10.1364/oe.25.002312
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发表时间：
2017-02-06
期刊：
影响因子：
3.8
通讯作者：
Phillips, M. C.
中科院分区：
文献类型：
--
作者：
Harilal, S. S.;LaHaye, N. L.;Phillips, M. C.
我们报告激光诱导荧光光谱（LIF）激光产生的等离子体在不同的氮压力水平到大气压力。等离子体是用Nd: YAG激光1064 nm， 6 ns脉冲在含有少量U和Al的玻璃靶上产生的。采用倍频连续波Ti：蓝宝石激光器作为超窄带可调谐LIF激发源，提高了激光等离子体中选定的U和Al原子跃迁的发射幅度和持久性。记录了不同氮气压力水平下的二维荧光光谱（2D-FS）吸收/发射图像，显示了激发和发射光谱特征。在较低的压力水平（100 Torr）下，荧光发射与热激发发射在时间上被很好地分离。然而，随着环境压力的增加，热激发发射持续时间延长，LIF发射持续时间和强度降低。激发光谱特征显示了等离子体中各种跃迁的固有线宽，其谱宽明显比发射光谱窄。我们评估了两个仅相隔18 pm的附近跃迁，以证明荧光光谱比热激发光谱在高分辨率研究中的有效性。目前的结果突出了LIF作为一种使用连续波激光再激发的诊断工具的重要性，解决了传统发射和吸收光谱方法的一些局限性。(C) 2017年美国光学学会
We report laser-induced fluorescence spectroscopy (LIF) of laser-produced plasmas under varying nitrogen pressure levels up to atmospheric pressure. The plasmas were generated on a glass target containing minor amounts of U and Al using 1064 nm, 6 ns pulses from a Nd: YAG laser. A frequency-doubled continuous- wave Ti: Sapphire laser was used as an ultra-narrowband tunable LIF excitation source to increase the magnitude and persistence of emission from selected U and Al atomic transitions in a laser-produced plasma. 2Dfluorescence spectroscopy (2D-FS) absorption/emission images were recorded at various nitrogen pressure levels, showing both excitation and emission spectral features. At lower pressure levels (100 Torr), fluorescence emission was found to be well separated in time from thermally-excited emission. However, as the ambient pressure increased, the thermally-excited emission persisted for longer times along with a reduction of LIF emission persistence and intensity. The excitation spectral features showed the inherent linewidths of various transitions in the plasma, which have significantly narrower spectral linewidths than observed in emission spectra. We evaluated two nearby transitions separated by only 18 pm to demonstrate the effectiveness of fluorescence spectra over thermally-excited spectra for high-resolution studies. The present results highlight the importance of LIF as a diagnostic tool employing continuous- wave laser re-excitation, addressing some of the limitations of traditional emission and absorption spectroscopic methods. (C) 2017 Optical Society of America