摘要
光声光谱技术是一种以光声效应为基础,具有响应速度快、测量时间短、检测灵敏度高等优点的新型光谱分析检测技术,已成为一种快速、安全、可靠的痕量气体检测手段。本文利用中心波长位于2.0μm的分布反馈式可调谐二极管激光器作为光源,搭建了二氧化碳(CO2)光声光谱测量系统,实验中采用对样品气体加湿的方式,通过引入弛豫速率快的H2O分子有效降低CO2分子的弛豫时间,增加了CO2气体的光声信号强度,提高了系统的探测灵敏度。测量中选取4998.35 cm^-1处的CO2吸收谱线为研究对象,结合波长调制技术,对CO2气体进行了探测研究。首先通过对系统的评估,确定了系统的最佳调制频率和最佳调制振幅为785 Hz和7.586 cm^-1。然后通过对一系列不同浓度的CO2-N2混合样品气体在最优实验条件下的测量研究发现,所测光声信号与CO2气体浓度之间具有良好的线性关系,进而反演出大气中CO2气体的含量,其浓度值约为3.82×10^-4。最后利用此系统对室外大气中CO2含量进行了连续24小时的连续实时测量,得到了CO2气体在一天中的浓度变化情况,并利用Allan方差对系统的长期稳定性进行了分析,当系统平均时间为1000 s时,探测灵敏度约为1×10^-7,证实了系统具有良好的稳定性和探测灵敏度。
Photoacoustic spectroscopy technology is a new type of spectral analysis detection technology based on the photoacoustic effect,which has the advantages of fast response,short measurement time,and high detection sensitivity.And it has become a fast,safe and reliable method for trace gas detection.In this paper,a distributed feedback tunable diode laser with a center wavelength of 2.0μm was used as the light source and a photoacoustic spectrometric system for measuring carbon dioxide(CO2)had been developed.In the experiment,the sample gas was humidified.And the relaxation time of CO2 molecules was reduced by introducing H2O molecules with fast relaxation rate,which can accelerate the relaxation rate of CO2 molecules and then improve the photoacoustic signal of CO2 gas and the detection sensitivity of the system.The CO2 absorption spectrum line at 4998.35 cm^-1 was selected as the research object in the measurement,combined with wavelength modulation technology,the CO2 gas was detected and studied.Firstly,the optimal modulation frequency and amplitude of the system were determined to be 785 Hz and 7.586 cm^-1 by evaluating the system.Then,it was found that there was a good linear relationship between the measured photoacoustic signal and the concentration of CO2 gas by measuring a series of CO2-N2 mixed sample gases under the optimal experimental conditions.And then the concentration of CO2 in the real atmosphere was measured by this system.And the content of CO2 in the outdoor atmosphere was about 3.82×10^-4.Finally,this system was also used to continuously measure the CO2 content in the outdoor atmosphere for 24 consecutive hours,and obtained the concentration change of CO2 gas in a day.And the long-term stability of the system was analyzed by using Allan Variance.The detection sensitivity was about 1×10^-7 when the average time of the system was 1000 s,which proved that the system had good stability and detection sensitivity.
作者
周鑫
刘新
吴陆益
喻雄
高光珍
蔡廷栋
ZHOU Xin;LIU Xin;WU Lu-yi;YU Xiong;GAO Guang-zhen;CAI Ting-dong(School of Physics and Electronic Engineering,Jiangsu Normal University,Xuzhou,Jiangsu 221116,China)
出处
《光电子．激光》
EI
CAS
CSCD
北大核心
2020年第12期1306-1312,共7页
Journal of Optoelectronics·Laser
基金
国家自然科学基金(61875079,61805110,61475068,11104237)
徐州市推动科技创新项目(KC19202)
江苏省研究生科研与实践创新计划项目(KYCX20_2221)
江苏省大学生创新创业训练计划项目(201810320072Z)资助项目。
关键词
光谱学
光声光谱
波长调制
二氧化碳
spectroscopy
photoacoustic spectroscopy
wavelength modulation
carbon dioxide
作者简介
蔡廷栋(1982-),男,山东临沂人,博士,教授,硕士生导师,主要从事高灵敏度光谱技术及应用和二极管激光气体传感技术应用等方面的研究.E-mail:caitingdong@126.com。
