NO2分子高灵敏度痕量探测技术研究

High-sensitive trace detection of NO2 with broadband cavity-enhanced spectroscopy

摘要: 搭建了一台基于蓝光LED的非相干宽带腔增强吸收光谱系统，并将其应用于NO2分子的高灵敏度痕量探测研究。在3 s采样时间下, 系统探测灵敏度为3.210-9 cm-1（1 ），对应NO2的探测极限约为187 pmol/mol。利用Allan方差对系统最佳采样时间及系统稳定性进行分析，当采样时间延长至30 s时，系统的探测极限可提高至44 pmol/mol。将该系统应用于实际大气中NO2的连续测量，其测量结果与商业化NOx分析仪（Thermo 42i）进行了比对测试。

Abstract: A blue light emitting diode (LED) based incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument was set up for high sensitive detection of NO2 molecule. A detection sensitivity of 3.210-9 cm-1 (1, 300 ms integrating time, and 10 times average) was demonstrated on the basis of absorption spectroscopy of NO2, corresponding to a minimum detection concentration of about 187 pmol/mol for NO2. The measurement sensitivity and optimum acquisition time of the IBBCEAS system were evaluated using Allan variance analysis. The detection limit of 44 pmol/mol for NO2 was achieved with an optimum acquisition time of 30 s. The IBBCEAS measured NO2 data in ambient air were compared to the values measured with an online NOx analyzer (Thermo 42i). Result shows a good agreement between the NOx analyzer and the IBBCEAS.