Temperature dependence of line broadening coefficient of chloromethane diluted in carbon dioxide

The chloromethane is one of the primary chlorine ion source in the upper atmosphere, and is on the watch list of the World Meteorological Organization regarding climate change monitoring. It originates both from natural sources, such as biomass burnings or tropical forests, and from human industrialization.
In this work, we studied line broadenings of chloromethane diluted in carbon dioxide in the QP branch of the ν1 band at low temperature (200K to room temperature). The spectra were recorded with a high resolution diode laser spectrometer.
To retrieve the broadening coefficients, we fitted theoretical line shape models on the experimental profiles. We used the common Voigt profile, as well as the Rautian and Sobel’man and the Galatry profiles. We then computed the temperature dependence coefficients.