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Atmospheric trace gas analysis with cavity ring‐down spectroscopy
Author(s) -
Kleine Daniel,
Mürtz Manfred,
Lauterbach Jörg,
Dahnke Hannes,
Urban Wolfgang,
Hering Peter,
Kleinermanns Karl
Publication year - 2001
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1560/r4db-ad8n-687h-105g
Subject(s) - chemistry , cavity ring down spectroscopy , overtone , trace gas , absorption (acoustics) , absorption spectroscopy , excimer laser , spectroscopy , laser , analytical chemistry (journal) , sideband , tunable diode laser absorption spectroscopy , optics , tunable laser , spectral line , microwave , physics , organic chemistry , chromatography , quantum mechanics , astronomy
Cavity ring‐down spectroscopy (CRDS) is a highly sensitive laser absorption method. It can be used for quantitative analysis of molecular species at the sub‐ppb level. The absorption cell (cavity) is sealed by two high‐reflective mirrors on each side, which results in an effective absorption path‐length of some kilometers. Our experiments for atmospheric gas analysis have been carried out so far with an Excimer pumped dye laser in the UV‐VIS and a CO overtone sideband laser in the wavelength region around 3 μm. Experiments with an all solid‐state difference frequency laser system will follow. In the UV‐VIS region, we measured trace gas molecules like SO 2 , NO 2 , and CH 2 O. In the mid‐infrared, around 3 μm, we measured hydrocarbons like CH 4 , C 2 H 6 , and C 2 H 4 with a detection limit of less than 1 ppb. The noise equivalent absorption coefficients in the MIR are in the order of 1.7·10 −9 cm −1 . Due to the high data acquisition rate and the high sensitivity, CRDS enables real‐time detection of trace gases in ambient air.