Accurate modeling of the diagnostic 118-GHz oxygen line for remote sensing of the atmosphere

•Outstanding SNR is achieved for the 118-GHz diagnostic line recordings in the 0.4-1000 Torr pressure range.•Clear manifestation of the SD effect was observed for this line.•A new line shape model was developed for taking into account SD and mixing effects.•Most accurate line shape parameters were retrieved for atmospheric applications.

We report the results of laboratory investigations of the shape of the diagnostic atmospheric N = 1- oxygen line performed over a very wide range of pressures from 0.4 to 1000 Torr using two principally different spectrometers having complementary abilities. A spectrometer with a radio-acoustic detector of absorption was used for recording low pressure spectra spanning the 0.4-2 Torr range, and high pressure data from 250 to 1000 Torr were registered by a resonator spectrometer. The sensitivity of both instruments was improved significantly which allowed us to obtain signal-to-noise ratio at spectra recordings of the order of a few thousands. The spectra analysis enabled the first manifestation of the speed-dependence of the collision cross section of the line, along with considerable refinement of other parameters, including pressure broadening, intensity and line-mixing. The results are of primary importance for atmospheric applications.