基于光声光谱技术的NO_(2)探测  

Nitrogen Dioxide Detection Based on Photoacoustic Spectroscopy

作　　者：孙柳雅 牛明生[1] 陈加雪 唐敏 尹亚婕 欧阳金华 Sun Liuya;Niu Mingsheng;Chen Jiaxue;Tang Min;Yin Yajie;Ouyang Jinhua(Shandong Provincial Key Laboratory of Laser Polarization and Information Technology,Laser Research Institute,School of Physical Engineering,Qufu Normal University,Qufu 273100,Shandong,China)

机构地区：[1]曲阜师范大学物理工程学院激光研究所山东省激光偏振与信息技术重点实验室,山东曲阜273100

出　　处：《中国激光》2022年第23期162-169,共8页Chinese Journal of Lasers

基　　金：山东省自然科学基金(ZR2018MD015);山东省重点研发计划(2017GSF17125);大学生创新实验项目(XJ20200071)。

摘　　要：提出了一种基于光声光谱技术的气体传感器,以444 nm蓝光激光器为激发光源,实现了对大气、汽车尾气中NO_(2)的检测及光解分析。对压强、NO_(2)体积分数与共振频率的关系进行了研究,验证了信噪比和光功率之间的线性关系,分析了光学斩波器的位置和相对湿度对光声信号的影响。通过Allan方差分析得到,当积分时间在100 s内时,传感器的检测限达到1×10^(-9)。在2 d内从上午8:00到下午6:00对大气中的NO_(2)进行了监测,与济宁市环境监测中心的数据吻合较好,最后检测了5辆汽车尾气中的NO_(2)含量以及光解前后的NO_(2)含量。实验结果表明,该传感器能够满足实际应用中NO_(2)探测的高灵敏度要求。Objective Nitrogen dioxide(NO_(2))is a crucial environmental pollutant.NO_(2)generated from automobile exhaust is a critical source of pollution,which has severely affected human health and influenced the quality of urban air and global climate change.The photoacoustic spectroscopy(PAS)based on the photoacoustic effect is a critical technology for trace gas detection owing to its benefits of zero background noise and high detection sensitivity.This study suggests a gas sensor based on PAS with a diode laser at 444 nm as the light source.The NO_(2)concentration in the atmosphere is monitored.NO_(2)concentrations emitted from various types of automobiles are compared,and the photolysis of NO_(2)is investigated.We hope that the findings of the study can offer a significant reference for the improvement of urban air quality and play a critical role in the comprehensive regulation of urban air pollution.Methods A diode laser with a central wavelength of 444 nm is employed as the excitation source,and an optical power meter behind the photoacoustic cell is employed to monitor the laser power’s stability.The optical chopper can modulate the optical intensity at the photoacoustic cell’s resonance frequency,and a reference signal(a square wave signal)is input to the lock-in amplifier.A microphone with a sensitivity of 45 m V/Pa is installed in the middle of the photoacoustic cell to detect the photoacoustic signal.The detected signal is amplified using a preamplifier and demodulated using a lock-in amplifier,and then collected and processed using the data acquisition card and a computer with Lab VEWI software.The vacuum pump,pressure controller,and mass flow controller are employed to regulate the pressure and flow of gas in the photoacoustic cell.A filter is installed in front of the gas inlet to prevent the interference of aerosols.Results and Discussions The photoacoustic signal intensity increases as the pressure and volume fraction of NO_(2)increase(Fig.3).The resonance frequency increases with the increase in pr

关 键 词：传感器 气体传感器 光声光谱法 蓝光激光器 NO_(2)探测 

分 类 号：O433[机械工程—光学工程]