差分吸收光谱法对大气中挥发性有机物光化学作用指示剂的监测与反演

Measurement and Retrieval of Indicators for Fast VOCs Atmospheric Photochemistry with Differential Optical Absorption Spectroscopy

差分吸收光谱技术(DOAS)由于高时间分辨率、高灵敏度和低操作费用等特点非常适合对大气中痕量的挥发性有机物(VOCs)的光化学作用指示剂——O3,Ox(O3+NO2)和HCHO进行实时追踪。但由于这些指示剂含量较低,测量精度易受干扰。文章利用自行研制的差分吸收光谱系统,对VOCs的光化学作用指示剂测量方法和数据反演进行了研究,通过增加信噪比,扣除背景杂散光等手段对其进行了准确测量;针对标准吸收截面的温度效应、光谱固有结构和灯谱结构的干扰,改进了干扰的对除方法;并对不同波段反演O3,NO2和HCHO的干扰因素,反演浓度结果和反演准确度进行了分析与对比,以合适的波段准确反演物质浓度。

Featuring excellent response characteristics and detection sensitivity and with much lower operational cost,differential optical absorption spectroscopy（DOAS） can be a powerful tool to trace concentration variation of trace indicators-O3,Ox（O3＋NO2） and HCHO for fast VOCs atmospheric photochemistry.But it＇s difficult to measure those gases accurately because of trace concentration.Here using a self-made DOAS system,the accurate measurement of those indicators was achieved through improving the ratio of signal to noise ratio and correcting the background scattering light;the retrieving method of those indicators was developed through eliminating the temperature effect of absorption cross section,accurately removing the intrinsic structure and lamp structure of spectrum.The preference of different spectral windows that could be used for the concentration retrieval of those indicators was analyzed and compared including interfering factors,results retrieved and the accuracy.