Experimental studies, line-shape analysis and semi-empirical calculations of broadening coefficients for (CH3Cl)-Cl-35-CO2 submillimeter transitions

Rotational transitions in (CH3Cl)-Cl-35 mixed with CO2 are recorded at 296 K and total pressures up to 0.6 Tort in the frequency interval 186-901 GHz (1.6-03 mm) for J=6 -> 7, 10 -> 11, 17 -> 18, 22 -> 23, 31 -> 32, 33 -> 34 and K=0-6, using the frequency-modulation spectrometer of the Laboratory PhLAM (Lille, France). These line-shapes are analyzed with the commonly used Voigt profile as well as with more refined Speed-Dependent Voigt and Galatry models accounting for the line narrowing induced, respectively, by the speed-dependence of the relaxation parameters and by velocity-changing collisions. Due to the high line intensities, the fitting procedure involves the full implementation of the Beer-Lambert law instead of its traditional linear approximation. The experimentally deduced J- and K-dependences of the pressure-broadening coefficients are further used to obtain the model parameters of a semi-empirical approach allowing massive calculations of line-shape parameters for enlarged ranges of rotational quantum numbers requested by spectroscopic databases. (C) 2014 Elsevier Ltd. All rights reserved.