Study On The Polarization Characteristics Of Laser-Induced Breakdown Spectroscopy Of Aluminum And Graphite

In this paper, based on the summarization and analysis of the research progress of laser-induced breakdown spectroscopy (LIBS) technique at home and abroad, we choose polarization-resolved laser-induced breakdown spectroscopy (PRLIBS) technique which can suppress the continuous emission by employing a polarizer in front of the detector to increase the signal-to-noise ratio (S/N) and signal-to-background ratio (S/B) of spectra because the continuum from laser induced plasma is much more polarized than discrete lines. The whole system of femtosecond PRLIBS and nanosecond PRLIBS which are used to research on aluminium alloy and graphite samples have been constructed. In our experiment, the effects of laser fluence, detection angle and incident laser polarization on the emission intensity and polarization of laser induced plasma are systematically explored. The non-statistical distribution of magnetic substates is used to explain the generation of polarized emission of atoms or ions in laser induced plasma.. The polarization of recombination radiation which is expressed by the differential cross section for recombination and the anisotropy of the electron velocity distribution with a net drift is used to explain the dependence of the polarization of laser induced plasma on laser fluence. The calculated result of polarization is in good agreement with the experimental observations.Our studies show the strongly polarized continuous emission of laser induced plasma and the excellent performance of PRLIBS technique on increasing the S/N and S/B ratio. The results obtained in our experiment can be used for further research on the characteristics of laser induced plasma and provide experimental basis for application of PRLIBS.