紫外LED光纤耦合长程DOAS系统监测大气SO_2和O_3的研究

Detection of Atmospheric SO_2 and O_3 Using Optical Fiber Coupling Long-Path Differential Optical Absorption Spectroscopy System with UV Light Emitting Diodes

介绍了一种基于发光二极管(LED)的光纤耦合长程差分吸收光谱(LP-DOAS)系统,用于测量大气中的SO2和O3。根据SO2和O3所在的吸收波段,选择了两种不同波长的紫外LED作为系统光源。当吸收光程为700m时,SO2和O3的探测限分别为0.8×10-9和7.4×10-9。将该系统测量结果与传统基于氙灯LP-DOAS的测量结果进行了对比,结果显示两者具有较好的一致性,测量SO2和O3的相关性分别为0.987和0.992。测量结果表明,通过光纤耦合方式来提高光源耦合效率后,采用以LED为光源的LP-DOAS系统来探测紫外波段的气体吸收是切实可行的。

The measurements of atmospheric sulphur dioxide （SO2） and ozone （O3） using optical fiber based on light- emitting diode （LED） long-path differential optical absorption spectroscopy （LP-DOAS） system are presented. Two ultraviolet （UV） LED with different emission wavelength ranges are used as the light sources. The measurement results are compared to the SO2 and O3 levels measured by the conventional LP-DOAS with xenon arc lamp light source. The comparison result shows that they are in good agreement, and the correlation coefficients of SO2 and O3 measurements are 0. 987 and 0. 992, respectively. With 700 m measurement path, the detection limit of SO2 and Oa are 0.8 ×10^-9 and 7.4 ×10^-9, respectively. This indicates that the optical fiber-based LP-DOAS improves the light coupling efficiency, and is feasible for the detection of ultraviolet absorbing trace gases using UV-LED as the light source.