Impact of Humidity on Quartz-Enhanced Photoacoustic Spectroscopy Based CO Detection Using a Near-IR Telecommunication Diode Laser

• Main Authors: Xukun Yin, Lei Dong, Huadan Zheng, Xiaoli Liu, Hongpeng Wu, Yanfang Yang, Weiguang Ma, Lei Zhang, Wangbao Yin, Liantuan Xiao, Suotang Jia
• Format: Article
• Language: English
• Published: MDPI AG 2016-01-01
• Series: Sensors
• Subjects: quartz enhanced photoacoustic spectroscopy; carbon monoxide; vibrational-to-translational (V–T) relaxation; near-IR telecommunication diode laser
• Online Access: http://www.mdpi.com/1424-8220/16/2/162
• ISSN: 1424-8220

A near-IR CO trace gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) is evaluated using humidified nitrogen samples. Relaxation processes in the CO-N2-H2O system are investigated. A simple kinetic model is used to predict the sensor performance at different gas pressures. The results show that CO has a ~3 and ~5 times slower relaxation time constant than CH4 and HCN, respectively, under dry conditions. However, with the presence of water, its relaxation time constant can be improved by three orders of magnitude. The experimentally determined normalized detection sensitivity for CO in humid gas is 1.556 × 10 − 8   W ⋅ cm − 1 / Hz 1 / 2 .