New infrared absorption cross sections for the infrared limb sounding of sulfur hexafluoride (SF6)

Abstract

Sulfur hexafluoride (SF6), widely used in industry for electrical insulation, is a potent greenhouse gas with a steadily increasing atmospheric abundance. In order to monitor its concentration profiles using infrared sounders, accurate laboratory spectroscopic data are required. This work describes new high-resolution infrared absorption cross sections of pure and air-broadened sulfur hexafluoride over the spectral range 780 – 1100 cm−1, derived from spectra recorded using a high-resolution Fourier transform spectrometer (Bruker IFS 125HR) and a 26-cm-pathlength cell. Spectra were recorded at resolutions between 0.002 and 0.03 cm−1 (calculated as 0.9/MOPD; MOPD = maximum optical path difference) over a range of atmospherically relevant temperatures (189 – 294 K) and pressures (up to 751 Torr). These new absorption cross sections improve upon those previously used for remote sensing, and will provide a more accurate basis for retrievals in the future.