Mobile Vehicle Measurement of Urban Atmospheric CH<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> Using a Midinfrared Dual-Gas Sensor System Based on Interband Cascade Laser Absorption Spectroscopy
Yan Ge, Lei Zhang, Chuantao Zheng, Mengyao Zhang, Kaiyuan Zheng, Fang Song, Weilin Ye, Yù Zhang, Yiding Wang, Frank K. Tittel
Abstract
A vehicle-mounted mobile mid-infrared dual-gas sensor system for simultaneous detection of methane (CH<sub>4</sub>) and ethane (C<sub>2</sub>H<sub>6</sub>) was developed using two interband cascade lasers (ICLs) for targeting the absorption line of CH<sub>4</sub> at 3038.5 cm<sup>-1</sup> and the line of C<sub>2</sub>H<sub>6</sub> at 2996.88 cm<sup>-1</sup>, respectively. Two multi-pass gas cells (MPGCs) with an absorption path length of 26.4 m were utilized. The detection limit (1σ) of CH<sub>4</sub> using wavelength modulation spectroscopy (WMS) is ~ 4.1 parts-per-billion by volume (ppbv) with a 0.5 s averaging time, and the detection limit (1σ) of C<sub>2</sub>H<sub>6</sub> is ~ 2.9 ppbv with a 0.5 s averaging time. Vehicle-mounted mobile measurement ability of the dual-gas sensor was enabled by a remote monitoring system based on an embedded Linux processor and a cloud server. Atmospheric CH<sub>4</sub> and C<sub>2</sub>H<sub>6</sub> monitoring was performed for 48 hours on the Jilin University campus to evaluate the performance of the sensor system. Vehicle-mounted mobile campaigns were carried out both on the Jilin University campus and in the Changchun Area for dual-gas concentration mapping. The sensor system shows the merits of remote monitoring and mobile gas sensing ability in field applications.