激光透射探针用于液相激光诱导击穿光谱全过程诊断及光谱校正

Overall Temporal Diagnostic and Spectral Normalization of Liquid Phase Laser-Induced Breakdown Spectroscopy Using Laser-Beam-Transmission Probe

液体环境中激光诱导击穿光谱(LIBS)包含等离子体辐射和膨胀、冲击波传输及气泡演化等过程,对其进行全过程时间分辨观测有助于理解液相LIBS物-化过程,并提高LIBS分析性能。为此,采用激光透射探针(LBTP)测量方法,通过连续氦氖激光器和光电探测器相结合,实现对单次LIBS过程中激光/等离子体辐射与冲击波/气泡演化的全过程时间分辨诊断。在不同激光脉冲能量激发下,比较同步采集的LBTP信号与LIBS信号,证明了LBTP信号负峰面积与LIBS特征峰面积之间存在较强的相关性(R^(2)>0.99)。在此基础上,对于不同浓度的碱金属离子水溶液,利用偏最小二乘回归(PLSR)法建立了LBTP信号对光谱特征峰面积相对偏差的回归模型,实现了LIBS信号波动校正。

Laser-induced breakdown spectroscopy(LIBS)inside liquids is accompanied by the emission and expansion of plasma,propagation of intense shockwaves,and growth of cavitation bubbles.A comprehensive time-resolved observation of these processes is essential to reveal the underlying physiochemical mechanism and improve the analytical performance of LIBS in liquids.In this work,by using a laser-beam-transmission probe(LBTP),a continuous wave He-Ne laser coupled with a photodiode are utilized to simultaneously record the transmission signals from the shockwave and bubble as well as the emission signals from the laser pulse and plasma during an individual LIBS event.Under the excitation of different laser pulse energies,the negative peak of the LBTP signal is proportional to the peak area of LIBS spectra with a relatively high correlation coefficient(R^(2)>0.99).On the basis of this approach,for aqueous alkali metal solutions with different concentrations,the regression model of LBTP signal to the relative deviation of spectral characteristic peak area is established by using partial least square regression(PLSR),and the LIBS spectral normalization is realized.