Pressure broadening of oxygen by water

Drouin, B., V. Payne, F. Oyafuso, K. Sung, and E. Mlawer (2014), Pressure broadening of oxygen by water, J. Quant. Spectrosc. Radiat. Transfer, 133, 190-198, doi:10.1016/j.jqsrt.2013.08.001.

A need for precise air-mass retrievals utilizing the near-infrared O2 A-band has motivated measurements of the water-broadening in oxygen. Experimental challenges have resulted in very little water broadened oxygen data. Existing water broadening data for the O2 A-band is of insufficient precision for application to the atmospheric data. Line shape theory suggests that approximate O2 pressure broadening parameters for one spectral region, such as the A-band, may be obtained from comparable spectral regions such as the O2 60 GHz Q-branch, which is also used prominently in remote sensing. We have measured precise O2–H2O broadening for the 60 GHz Q-branch and the pure-rotational transitions at room temperature with a Zeeman-modulated absorption cell using a frequency-multiplier spectrometer. Intercomparisons of these data and other O2 pressure broadening data sets confirm the expectation of only minor band-to-band scaling of pressure broadening. The measurement provides a basis for fundamental parameterization of retrieval codes for the long-wavelength atmospheric measured values. Finally, we demonstrate the use of these measurements for retrievals of air-mass via remote sensing of the oxygen A-band.

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