中文摘要：

基于湿化学采样及光学检测的方法，自行搭建了长光程吸收光谱仪（LOPAP）用于检测痕量的亚硝酸．该仪器成本低，响应时间快，灵敏度高，检测限低，可以连续测量并且排除了现有其他仪器存在干扰影响的问题。既能够对大气中的痕量亚硝酸进行测量，又能检测例如烟雾箱和废气中高浓度的亚硝酸．该仪器采用双通道系统，通过将两个通道测量信号相减可以减小测量中未知干扰物的影响．仪器的检测限可以达到9×10^-12mol·mol^-1，响应时间为5min，其准确度为±10％．另外对NO、N02、O3、NO2＋O3、NO2＋SO2、O3＋HONO等气体进行了仪器的干扰分析，发现只有当NO2存在时才有很弱的HONO干扰信号产生，干扰值大约为0．02％．同时在2013年8月29日到9月4日对HONO在中国科学院化学研究所进行了为期六天的外场观测，分析了HONO的日浓度变化，以及这种变化与光照强度、NOx浓度和NO2浓度之间的关系．HONO／NO2的比率表明除了NO2的非均相反应外还存在未知来源．

英文摘要：

Nitrous acid （HONO） is an important trace gas in tropospheric photochemistry, which plays a significant role in polluted urban atmosphere. Based on the measuring principle, a long path absorption photometer （LOPAP） for the detection of nitrous acid was built inhouse, which uses wet chemical sampling and photometric detection. This instrument aims to overcome the known problems with current HONO measurement techniques and was designed to be a cheap, sensitive, compact, and continuously working HE）NO monitor for ambient air measurements in the troposphere, or for measurements of higher concentration, e.g., in a smog chamber and in exhaust gases. The system includes two channels, by subtracting the signal of the second channel from the first channel the occurrence of possible unknown interferences can be minimized. The instrument has a detection limit of 9×10^-12 mol· mol^-1 and an accuracy of 10% at 5 min resolution, with a good linear relationship exhibited. In addition, we tested probable interferences from NO, NO2, O2, NO2＋O3, NO2＋SO2, and O3＋HONE）. It was found that there were interference signals only when NO2 existed （value about 0.02%）. With the instrument, 6 days of field observation was performed at the Institute of Chemistry, Chinese Academy of Sciences, Beijing, from 29 August to 4 September, 2013. During the observation we analyzed the diurnal variation of the HONO concentration and the correlation between the HONO concentration and solar radiation intensity, and the concentrations of NOx and NO2. Results from the ratio of HONO/NO2 indicate unknown HONO sources, except for the heterogeneous reaction of NO2.