title: High-resolution spectra of bromo methane and methyl bromide obtained by a continuously tunable 10-bar CO2 laser based photoacoustic spectrometer.
abstract: High resolution spectral data of 100 ppmV (10(-6) per volume) concentrations of the trace gases bromo methane (BM, CH3Br), and methyl bromide (DME, (CH3)2O), buffered in synthetic air (80% N2, 20% O2) at atmospheric pressure and room temperature are reported. The spectra are recorded with a continuously tunable 10-bar CO2 laser based photoacoustic (PA) spectrometer. The tuning range covers 76 cm(-1) between 9.2 microm (1087 cm(-1)) and 10.7 microm (935 cm(-1)) at a constant narrow line-width of 0.018 cm(-1) (540 MHz). The non-resonant PA measuring cell employs an in-line 10-microphone array. The estimated detection limits for BM and DME are approximately 2 ppmV for a signal-to-noise ratio (SNR) of 3. This corresponds to a calculated detection limit of approximately 76 ppbV for ethylene.
authors.affiliation: Swiss Federal Institute of Technology ETH, Institute of Quantum Electronics, Laboratory for Laser Spectroscopy and Environmental Sensing, Zürich.
authors.forename: A
authors.initials: A
authors.lastname: Romann
authors.forename: M W
authors.initials: MW
authors.lastname: Sigrist