DETECTION OF H2S AT THE PPM LEVEL USING A TELECOMMUNICATION DIODE-LASER

Detection of traces of H2S in air at the ppm level using a Distributed -Feed-Back (DFB) semiconductor diode laser spectrometer is reported. T wo-tone frequency modulation spectroscopy is employed to investigate o vertone transitions of H2S near lambda = 1580 nm and a sensitivity of 4 ppm.m for the 1577.32 nm component of the nu(1) + nu(2) + nu(3) band is achieved. This result improves the optical detection limit of H2S in air by one order of magnitude. Self- and air-broadening coefficient s at 25 degrees C are determined with direct absorption spectroscopy. (C) 1998 Elsevier Science B.V.