湿度和SF_6在石英增强光声光谱中对CO分子弛豫率的影响

Impact of humidity and SF_6 on CO detection based on quartz-enhanced photoacoustic spectroscopy

为了研究六氟化硫(SF_6)气体分子和水汽(H_2O)对一氧化碳(CO)气体分子的弛豫率的影响,建立了一个基于石英增强光声光谱(QEPAS)技术的痕量气体传感器系统。采用1.57μm的近红外分布式反馈二极管激光器作为激励光源,并对不同SF_6和H_2O气体浓度下的CO的光声信号进行对比研究。首先用CO传感器系统探测CO与N_2的气体混合物中CO的光声信号,然后在CO与N_2气体混合物中加入不同浓度的SF_6气体,分别探测不同浓度SF_6气体下的CO光声信号强度。最后在CO与N_2的气体混合物中加入不同浓度H_2O,探测加入H_2O后的CO的光声信号强度。实验结果表明随着CO和N_2气体混合物中SF_6气体浓度的增加,CO的光声信号幅值几乎没有变化,而在混合物中加入2.5%的H_2O后,发现CO的光声信号提高了约5倍。因此,SF_6对CO气体的弛豫率没有明显的影响,然而H_2O的添加能够有效缩短CO气体的弛豫时间。

A CO sensor system based on quartz-enhanced photoacoustic spectroscopy technology was established to study the effect of sulfur hexafluoride(SF 6)and water vapor(H 2O)on the relaxation rate of carbon monoxide(CO)gas molecules.A 1.57μm near-infrared distributed feedback diode laser was used as the light source to compare the photoacoustic signal amplitudes of CO under different concentrations of SF 6 and H 2O.First,a CO sensor system was used to detect photoacoustic signals from CO in a gas mixture of CO and N 2.Then,different concentrations of SF 6 gas were added to the CO and N 2 gas mixture and the photoacoustic signal amplitudes of CO were detected.Finally,H 2O was added to the gas mixture of CO and N 2 before detecting the photoacoustic signal amplitudes of CO.The experimental results show that with increasing concentration of SF 6 in the gas mixture of CO and SF 6,the photoacoustic signal of CO remains constant;however,the addition of 2.5%H 2O to the mixture results in a five-fold increase of the photoacoustic signal of CO.Therefore,H 2O has an obvious effect on the relaxation rate of CO gas,while SF 6 has none.