Line parameters for CO_{2} and selfbroadening in the ν_{1} band of HD^{16}O
Abstract
Lorentz halfwidth coefficients and their temperature dependence exponents for CO_{2} broadening in the fundamental bands of HDO are important for reliable and accurate interpretation of Mars and Venus atmospheric data and to determine D/H. Uncertainties in the temperature dependences of the CO_{2}broadened halfwidth coefficients lead to large errors in the retrieved mixing ratios and hence in HDO column abundances. In this highresolution FTIR laboratory study, we report first measurements of the temperature dependences of halfwidth coefficients for HDO transitions in the ν_{1} and 2ν_{2} bands broadened by CO_{2}. Accurate line positions, intensities, CO_{2}broadened width and pressure shift coefficients, their temperature dependences, collisional line mixing coefficients for HDOCO_{2} system and quadratic speed dependence parameters have been retrieved for a large number of transitions in the ν_{1} band. Roomtemperature selfbroadened halfwidth coefficients, selfshift coefficients, and collisional linemixing coefficients for HDOHDO system were also measured for the same number of ν_{1} transitions. Positions and intensities were measured for nearly 60 transitions in the weaker 2ν_{2} band along with a few roomtemperature measurements of CO_{2} and selfbroadening and pressureshift coefficients. These results were obtained from simultaneous nonlinear least squares fittings of ten highresolution absorption spectra recorded with the Bruker IFS125HR FTS at JPL and two coolable sample cells. Modified Complex RobertBonamy (MCRB) formalism was applied to compute both types of broadening and pressure shift coefficients, and the temperature dependences of the CO_{2} and selfbroadening parameters. Present measurements are compared with the MCRB calculations and other theoretical values reported in the literature.
 Publication:

Journal of Quantitative Spectroscopy and Radiative Transfer
 Pub Date:
 December 2017
 DOI:
 10.1016/j.jqsrt.2017.01.032
 Bibcode:
 2017JQSRT.203..133D
 Keywords:

 HDOCO<SUB>2</SUB> widths;
 HDOCO<SUB>2</SUB> shifts;
 HDOCO<SUB>2</SUB> MCRB calculated list;
 Temperature dependence exponents;
 Mars atmosphere