Methyl Chloride ν5Region Lineshape Parameters and Rotational Constants for the ν2, ν5, and 2ν3Vibrational Bands

Abstract Fourier spectra of methyl chloride have been obtained at ambient laboratory temperature under self-broadening conditions. Five thousand two hundred and sixty rovibrational transitions of the (ν 2 , ν 5 , 2ν 3 )-vibrational-band triad have been assigned, and new ground and excited state rotational constants for CH 3 35 Cl and CH 3 27 Cl have been determined. The ν 5 and ν 2 vibrational-band intensities are determined to be, respectively, 42(1.2) and 31.7(0.9) cm −2 atm −1 . Self-broadening coefficients of individual rovibrational lines are determined for the ν 5 band of CH 3 35 Cl and CH 3 37 Cl at 296 K. The self-broadening coefficients peak broadly close to the maximum in the Boltzmann rotational population; no specific trends of the broadening coefficients are observed with the rotational quantum number K . With the exception of the R Q ( J , 0) branch, the 1260–1650 cm −1 spectral region can be well modeled by the superposition of overlapping Voigt line profiles. To adequately model the densely packed R Q ( J , 0) branch, however, we included collisional line mixing with A + to A − in addition to A − to A − and A + to A + |Δ J | ≥ 1, Δ K = 0 collisional transitions allowed.