Lei Bingying, Xu Boping, Wang Jing, Li Jing, Wang Yishan, Tang Jie, Zhao Wei, Duan Yixiang
State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS Xi'an 710119 China
School of Future Technology, University of Chinese Academy of Sciences Beijing 100049 China.
RSC Adv. 2020 Oct 28;10(65):39553-39561. doi: 10.1039/d0ra06582j. eCollection 2020 Oct 27.
A single-beam-splitting approach was used to enhance the signal intensity of LIBS under the extreme conditions of laser beam grazing of the surface of non-flat samples. Time-resolved spectra show that the laser-ablated plasma presents a stronger spectral intensity and a slower plasma decay in the split beam mode because of the higher laser irradiance. The temporal evolutions of signal enhancement factors indicate that the enhancement effect first rises and then drops with delay time and the maximum enhancement factor of Al plasma comes later than that of Cu plasma under the same laser energy. The mechanisms behind it are discussed. It is also found that the electron density exhibits a faster decay with delay time in the split beam mode, mainly due to the faster plasma expansion. And a slower increase of electron density with laser energy is observed in the split beam mode because of the plasma shielding effect.
在非平面样品表面激光束掠射的极端条件下，采用单光束分光方法来增强激光诱导击穿光谱（LIBS）的信号强度。时间分辨光谱表明，由于更高的激光辐照度，在分束模式下激光烧蚀产生的等离子体呈现出更强的光谱强度和更慢的等离子体衰减。信号增强因子的时间演化表明，增强效应随延迟时间先上升后下降，并且在相同激光能量下，铝等离子体的最大增强因子比铜等离子体出现得晚。文中讨论了其背后的机制。还发现，在分束模式下电子密度随延迟时间呈现更快的衰减，这主要是由于等离子体的更快膨胀。并且由于等离子体屏蔽效应，在分束模式下观察到电子密度随激光能量的增加更慢。
