Detection of H 2S at the ppm level using a telecommunication diode laser

Abstract

Detection of traces of H 2S in air at the ppm level using a Distributed-Feed-Back (DFB) semiconductor diode laser spectrometer is reported. Two-tone frequency modulation spectroscopy is employed to investigate overtone transitions of H 2S near λ = 1580 nm and a sensitivity of 4 ppm·m for the 1577.32 nm component of the ν 1+ ν 2+ ν 3 band is achieved. This result improves the optical detection limit of H 2S in air by one order of magnitude. Self- and air-broadening coefficients at 25°C are determined with direct absorption spectroscopy.