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New and improved infrared absorption cross sections for chlorodifluoromethane (HCFC-22)

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journal contribution
posted on 09.11.2016, 12:25 by Jeremy J. Harrison
The most widely used hydrochlorofluorocarbon (HCFC) commercially since the 1930s has been chlorodifluoromethane, or HCFC-22, which has the undesirable effect of depleting stratospheric ozone. As this molecule is currently being phased out under the Montreal Protocol, monitoring its concentration profiles using infrared sounders crucially requires accurate laboratory spectroscopic data. This work describes new high-resolution infrared absorption cross sections of chlorodifluoromethane over the spectral range 730-1380 cm-1, determined from spectra recorded using a high-resolution Fourier transform spectrometer (Bruker IFS 125HR) and a 26 cm pathlength cell. Spectra of chlorodifluoromethane/dry synthetic air mixtures were recorded at resolutions between 0.01 and 0.03 cm-1 (calculated as 0.9/MOPD; MOPD denotes the maximum optical path difference) over a range of temperatures and pressures (7.5-762 Torr and 191-295 K) appropriate for atmospheric conditions. This new cross-section dataset improves upon the one currently available in the HITRAN (HIgh-resolution TRANsmission) and GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques) databases; in particular it provides coverage over a wider range of pressures and temperatures, has more accurate wavenumber scales, more consistent integrated band intensities, improved signal to-noise, is free of channel fringing, and additionally covers the v2 and v7 bands.

Funding

The author wishes to thank the National Centre for Earth Observation (NCEO), funded by the UK Natural Environment Research Council (NERC), for supporting this work and for access to the Molecular Spectroscopy Facility (MSF) at the Rutherford Appleton Laboratory (RAL),

History

Citation

Atmospheric Measurement Techniques, 2016, 9 (6), pp. 2593-2601

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Atmospheric Measurement Techniques

Publisher

European Geosciences Union (EGU), Copernicus Publications

issn

1867-1381

eissn

1867-8548

Acceptance date

06/05/2016

Copyright date

2016

Available date

09/11/2016

Publisher version

http://www.atmos-meas-tech.net/9/2593/2016/

Notes

The new HCFC-22 dataset is available electronically from the author and will be made available to the community via the HITRAN and GEISA databases.

Language

en

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