Abstract:
The H$_2$O–CO$_2$ line shape parameters are necessary for studying the planetary atmospheres in which carbon dioxide is the main gas. H$_2$O absorption lines broadened by the pressure of carbon dioxide were recorded using the IFS 125 HR Fourier spectrometer in the range of 8830–9000 cm$^{-1}$. A modified Voigt profile taking into account the dependence of broadening on the relative speed of the colliding molecules was used to approximate the lines. For the first time the parameters of the H$_2$O absorption lines belonging to the $\nu_1+\nu_2+\nu_3$, $2\nu_1+\nu_2$, $6\nu_2$, $\nu_1+3\nu_2$$3\nu_2+\nu_3$ vibrational-rotational bands were determined. The calculations of the broadening coefficients were carried out using a semi-empirical method which uses a correction factor depending on the quantum numbers. The computed room-temperature broadening coefficients of water vapor lines induced by carbon-dioxide pressure are presented; the rotational quantum number of angular momentum J varies from 0 to 9.
Keywords:water vapor, Martian atmosphere, Venusian atmosphere, line broadening, H$_2$O–CO$_2$.
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