Line-shapes and broadenings of rotational transitions of (CH3Cl)-Cl-35 in collision with He, Ar and Kr

Rotational lines of methyl chloride (CH3Cl)-Cl-35 in collision with He, Ar, and Kr have been recorded at room temperature in the 186-901 GHz range (6.2-30.1 cm(-1)) for J=6 -> 7, 10 -> 11, 17 -> 18, 22 -> 23, 31 -> 32, 33 -> 34 and K=0-6. Owing to the high sensitivity of the frequency-modulated spectrometer used, clear deviations of the recorded line-shapes from the usual Voigt profile have been observed and their additional analyses with more refined models (Speed-Dependent Voigt, Galatry and Speed-Dependent Galatry profiles) have been performed. It has been evidenced that the observed line-shapes are mainly governed by the speed-dependence of relaxation rates (''wind effect'') and that the optical diffusion related to velocity changing collisions (Dicke effect) has a nearly negligible role. (C) 2015 Elsevier Ltd. All rights reserved.