Mobile Vehicle Measurement of Urban Atmospheric CH4/C2H6 Using a Midinfrared Dual-Gas Sensor System Based on Interband Cascade Laser Absorption Spectroscopy

A vehicle-mounted mobile mid-infrared dual-gas sensor system for simultaneous detection of methane (CH₄) and ethane (C₂H₆) was developed using two interband cascade lasers (ICLs) for targeting the absorption line of CH₄ at 3038.5 cm^-1 and the line of C₂H₆ at 2996.88 cm^-1, respectively. Two multi-pass gas cells (MPGCs) with an absorption path length of 26.4 m were utilized. The detection limit (1σ) of CH₄ 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 C₂H₆ 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 CH₄ and C₂H₆ 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.