Quantitative analysis of atmosphere by laser—induced breakdown spectroscopy

In order to investigate the feasibility of quantitative analysis with laser—induced breakdown spectroscopy， plasmas were produced by a Q—switched Nd ：YAG laser interacted with the air at atmospheric pressure，then the light of plasmas entered the monochrom eter and transferred into an electric signal，and the spectra of these plasmas in the range of 600～ 800 nm were stored and analyzed by the calibration—free mode1．Under the condition of delay time of 8 s and gating pulse of 0．4 s，the
temperature of plasmas，which was in local thermal equilibrium (LTE)，was 1．62× 10 K which was obtained by means of the two—dimensional Boltzmann plane．The 20．75 oxygen content and 79．25％nitrogen content in air were detected on the assum ption that there were only oxygen and nitrogen constituents in the air．The results coincide well with the fact．The feasibility was validated by the experiment，and it built a strong basis for the further study and experiment of air pollutant monitoring．