液相激光诱导击穿光谱的成像探测及图像辅助分析方法

Imaging detection and image-assisted analytical method for laser-induced breakdown spectroscopy in liquid

激光诱导击穿光谱(LIBS)技术用于液体样品探测时,存在光谱信号稳定性差和重复性差的问题,限制了该技术的实际应用。为了提升液相LIBS的稳定性,基于等离子体直接成像和气泡投影成像探测方法,采集了光谱与后向(Coaxial)、侧向(Lateral)等离子体图像及气泡图像的同步数据,并对光谱强度与3类图像的强度和形态特征之间的相关性进行了分析,结果表明后向等离子体图像的总辐射强度与光谱强度的相关性最高;在此基础上利用后向等离子体图像信息对光谱强度进行校正,光谱强度(Li I 670.8nm)的相对偏差由10.24%降低为4.14%,且LIBS的定量分析性能也有所提升,从而证明了图像辅助的光谱校正方法应用于液相LIBS分析的可行性。

Laser-induced breakdown spectroscopy in liquid commonly suffers from poor measurement repeatability and reproducibility,which is an obstacle to its practical application.In order to improve the stability of LIBS in liquid medium,the spectra were acquired synchronously with coaxial plasma images,lateral plasma images or shadowgraphs of bubble,by exploiting the fast imaging and shadowgraph techniques.The correlations between the spectral line intensity and the intensity or morphology of the three types of images were analyzed.The results showed a good linear relationship between the spectral line intensity and the sum intensity of coaxial plasma image.Thereafter,the coaxial plasma images were used to correct the spectral line intensity(Li I 670.8 nm),leading to a decrease of the relative standard deviation from 10.24%to 4.14%.Moreover,an improvement of quantitative performance had also been observed,which demonstrated the availability of such image-assisted spectral correction method in LIBS analysis of liquid samples.