NO2分子高灵敏度痕量探测技术研究

 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3.2×10-9 cm-1（1 σ），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。

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

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 3.2×10-9 cm-1 (1σ, 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.