Laser-induced dispersive fluorescence spectrum and the detection of NO2
会议名称：《2007亚洲光电子会议高能激光器及应用分会场》
会议日期：2007年
学科分类：080901[工学-物理电子学] 0809[工学-电子科学与技术（可授工学、理学学位）] 08[工学] 080401[工学-精密仪器及机械] 0804[工学-仪器科学与技术] 0803[工学-光学工程]
关 键 词：laser induced dispersive fluorescence spectrum NO2 quenching mechanism limit of detection
摘 要：Laser-induced dispersive fluorescence(LIDF)spectrum of NO2 molecule in the spectral region of 508.3-708.3nm is obtained with the 508.0nm excitation wavelength. It is found that at low sample pressure the spectrum is composed of a banded structure superimposed on a continuous one. While the spectrum show itself as a continuous envelope centered at 630.0nm when the pressure with a higher value. NO2 molecules are excited to the first excited state A2B2 by absorbing laser photons. Owing to the strong interaction between X2A12B2 and A2B2 B2B1states, some excited molecules redistribute to X2A1 and B2B1 states by the process of internal energy conversion or quenching. This induces the fluorescence come from different excited states. Based on the experimental data, the vibration frequencies of the ground electronic state of NO2 molecule are obtained. They are ω1=(1319±12)cm-1, ω2=(759.8±0.7)cm-1,and ω3=(1635±29)cm-1. The optimum-receiving wavelength for detecting NO2 gas with the technique of LIDF is proposed.