Off-beam quartz-enhanced photoacoustic spectroscopy-based sensor for hydrogen sulfide trace gas detection using a mode-hop-free external cavity quantum cascade laser

Abstract

Hydrogen sulfide (H2S) trace gas detection based on off-beam quartz-enhanced photoacoustic spectroscopy using a continuous wave (CW), mode-hop-free external cavity (EC) quantum cascade laser tunable from 1310 to 1210 cm−1 was performed. A 1σ minimum detection limit of 492 parts per billion by volume (ppbv) using a 1 s lock-in time constant was obtained by targeting the line centered at 1234.58 cm−1. This value corresponds to a normalized noise equivalent absorption coefficient for H2S of 3.05 × 10−9 W cm−1 Hz−1/2.