Line mixing in the QQ sub branches of the ν1 band of methyl chloride

Line-mixing effects have been studied in the nu(1) (Q)Q(K) (K from 0 to 10) sub branches of methyl chloride (CH3Cl) perturbed by nitrogen (N-2). Laboratory Fourier transform spectra have been recorded at room temperature for various pressures of atmospheric interest. In order to accurately model these spectra, a theoretical approach accounting for line-mixing effects is necessary and proposed in this study. The common model used in this work is based on the state-to-state rotational cross-sections calculated by a statistical modified exponential-gap fitting law depending on few empirical parameters. These parameters have been deduced by least-squares fitting a sum rule to the N-2-broadening coefficients modeled previously. Comparisons between experimental and calculated spectra for various (Q)Q sub branches at various pressures of N-2 demonstrate the adequacy of the model as compared to the use of the Voigt profile. (C) 2012 Elsevier Ltd. All rights reserved.