差分吸收光谱中甲醛的反演研究

Study of Retrieving Formaldehyde with Differential Optical Absorption Spectroscopy

由于甲醛(HCHO)在城市大气光化学反应中的重要性,测量大气环境中的甲醛已经成为全球的热点。针对目前国内检测甲醛的方法基本局限于化学法,文章详细介绍了采用差分吸收光谱(DOAS)技术反演得到大气环境中甲醛的方法,利用自制的差分吸收光谱系统测量了北京地区大气中的甲醛。文章分析了DOAS反演过程中反演甲醛光谱波段的选择及去除大气中SO2,NO2,O3的吸收以及氙灯灯谱结构对光谱反演中的交叉干扰影响;通过采用选择不同干扰气体所对应的最优波段,同时反演获得大气环境甲醛的浓度,避免了甲醛选择波段过窄,干扰气体去除不全的缺点;通过对误差来源的分析,得到该甲醛的反演方法总误差在13.7%内。

The present paper introduces the method of retrieving the concentration of HCHO with differential optical absorption spectroscopy（DOAS）.The authors measured ambient HCHO in Beijing region with the help of differential optical absorption spectroscopy instrument made by ourself,and discussed numerous factors in retrieving the concentration of HCHO with differential optical absorption spectroscopy（DOAS）,especially,the choice of HCHO wave band,how to avoid absorption of ambient SO2,NO2 and O3,and the influence of the Xenon lamp spectrum structure on the absorption of ambient HCHO.The authors achieved the HCHO concentration by simultaneously retrieving the concentrations of HCHO,SO2,NO2 and O3 with non-linear least square fitting method,avoiding the effect of choosing narrow wave of HCHO and the residual of SO2,NO2,O3 and the Xenon lamp spectrum structure in retrieving process to attain the concentration of HCHO,Finally the authors analyzed the origin of error in retrieving the concentration of HCHO with differential optical absorption spectroscopy（DOAS）,and the total error is within 13.7% in this method.