基于O2-O2吸收的非相干宽带腔增强吸收光谱浓度反演方法研究  

A concentration retrieval method for incoherent broadband cavity-enhanced absorption spectroscopy based on O_2-O_2 absorption

作　　者：凌六一[1,2] 谢品华[2,3] 林攀攀 黄友锐[1] 秦敏[2] 段俊[2] 胡仁志[2] 吴丰成[2] 

机构地区：[1]安徽理工大学电气与信息工程学院,淮南232001 [2]中国科学院安徽光学精密机械研究所,中国科学院环境光学与技术重点实验室,合肥230031 [3]中国科学技术大学环境科学与光电技术学院,合肥230031

出　　处：《物理学报》2015年第13期82-88,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:41305139,61108031,41275038);安徽省自然科学基金(批准号:1408085QD75);中国科学院战略性先导科技专项(B类)(批准号:XDB05040200);国家高技术研究发展计划(863计划)(批准号:2014AA06A511,2014AA06A508);中国科学院环境光学与技术重点实验室开放基金(批准号:2005DP173065-2013-05)资助的课题~~

摘　　要：针对传统非相干宽带腔增强吸收光谱浓度反演方法的定量结果易受镜片反射率标定误差的影响问题,提出了一种基于测量大气O2-O2吸收的浓度反演方法.该方法是将非相干宽带腔增强吸收光谱技术的光学增强腔等效成吸收光程不随波长变化的多次反射池,首先根据测得的宽带腔增强大气吸收谱和参考谱计算出光学厚度,并应用差分光学吸收光谱算法拟合修正后的气体吸收截面到光学厚度,反演得到大气中O2-O2以及被测气体的柱浓度,然后根据O2-O2在大气中的含量已知且相对稳定这一特性,确定出等效多次反射池的吸收光程,最后从被测气体的柱浓度中扣除吸收光程信息得到被测气体的浓度值.以监测大气中NO2实验为例,应用该方法在454—487 nm波段反演得到了大气NO2的浓度(1—30 ppbv范围内),并将反演结果与传统浓度反演方法的结果进行了对比,发现两者的不一致性在7%以内.实验结果表明,非相干宽带腔增强吸收光谱技术可以利用大气O2-O2的吸收来定量其他被测气体的浓度,而且定量结果对镜片反射率的标定误差不敏感.Incoherent broadband cavity-enhanced absorption spectroscopy （IBBCEAS） has a very high detection sensitivity, nevertheless the quantitative results retrieved by the traditional concentration retrieval method are affected by the calibration error of mirror reflectivity. Therefore, in this paper we present another concentration retrieval method based on the measurements of atmospheric O2-O2 absorption. In this method the optical cavity of IBBCEAS is equivalent to a multi-reflection cell, in which the optical path length is independent of the wavelength, i.e. a constant. First, we get the slanting column concentrations of atmospheric O2-O2 and other trace gases measured by using the differential optical absorption spectroscopy （DOAS） to fit the corrected cross sections of the measured gases to the optical density from the IBBCEAS absorption spectra and reference spectra. Second, the optical path length of an equivalent cell is determined by the known concentrations of O2-O2 in the atmosphere. Third, the concentrations measured for trace gases are retrieved by the deduction of absorption optical path length from the obtained slanting column concentrations. The above method is demonstrated by measuring the atmospheric NO2 with an IBBCEAS instrument in the range of 454—487 nm. Atmospheric NO2 concentrations retrieved by this method are compared with those by the traditional method, and the difference between them is shown to be less than 7%. Experimental results show that the absorption of atmospheric O2-O2 can be used to quantify other trace gases when measured by IBBCEAS, and, above all, the quantitative results are almost insensitive to the calibration error from mirror reflectivity.

关 键 词：非相干宽带腔增强吸收光谱技术 浓度反演 大气O2-O2 NO2探测 

分 类 号：O433.51[机械工程—光学工程]