摘要
基于石英增强光声光谱技术,以中心波长为2.0μm的窄线宽分布反馈式半导体激光器(DFB)为激励光源,采用波长调制及二次谐波解调技术通过改变激光器工作电流实现波长扫描完成了痕量CO2气体检测系统,并通过优化实验参数确定了常压下激光最佳调制深度,实现了高灵敏CO2浓度的检测。通过改变待测气体中的水汽浓度,研究了水汽对CO2气体探测结果的影响,结果显示在水汽浓度低于0.2%范围内,CO2气体光声信号随H2O浓度的上升而明显增强,当浓度高于此值后,H2O浓度的增加对CO2光声信号的增强作用几乎维持不变。数据显示,常温常压下H2O分子通过提高分子弛豫率最多可将二氧化碳R16吸收线的光声信号幅值提高约2.1倍。优化后的装置可以很好的实现大气中CO2浓度的检测。该装置获得的最小探测灵敏度为19ppm(1σ,300ms积分时间),相应的归一化噪声等效吸收系数为4.71×10-9 cm-1·W·Hz-1/2。
A carbon dioxide（CO2）sensor is developed using quartz enhanced photoacoustic spectroscopy（QEPAS）with a 2.0μm distributed feedback diode laser.The detection is based on a 2f wavelength-modulation spectroscopy approach by dithering and scanning the laser current.The laser modulation depth is optimized at normal atmosphere pressure and room temperature.The influence of the H2 O presence in the sample gas mixture on the CO2 sensor performance is also investigated.The results show that,with 1% CO2 concentration,the H2 O in the concentration ranges of 0to 0.2% has an effect on the CO2 signal amplitude and phase,and the largest amplitude difference is～2.1times.When the H2 O concentration is over 0.2%,the CO2 signal amplitude is saturated and remains steady.Atmospheric CO2 concentration is well measured using the optimal sensor parameters.Benefiting from the strong absorption line intensity at 4 989.97cm^-1,a detection limit of 19ppm（1σ,300 ms averaging time）is achieved,which corresponds to a normalized noise equivalent absorption coefficient of 4.71×10^-9 cm^-1·W·Hz^-1/2.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2015年第8期2078-2082,共5页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(61275213
61108030
61275154)
山西省自然科学基金项目(2013021004-1)
山西省回国留学人员科研资助项目(2013-011)
山西省留学回国人员科技活动资金项目(2013-01)
浙江省公益性项目(2014C31025)资助
关键词
石英增强光声光谱
2.0μm分布反馈激光器
气体传感器
分子弛豫率
Quartz-enhanced photoacoustic spectroscopy
2.0μm distributed feedback semiconductor laser
Gas sensors
Molecular relaxation rate
