Abstract
The most widely used hydrochlorofluorocarbon (HCFC) commercially since the
1930s has been chloro-difluoromethane, 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 ν2 and ν7 bands.
Citation
ID:
134066
Ref Key:
harrison2016atmosphericnew