Temperature dependences of N-2-broadening and shift coefficients in the v(6) perpendicular band of (CH3D)-C-12

The temperature-dependences of line broadening and shift parameters for many (CH3D)-C-12 transitions have been determined using six high-resolution, high signal-to-noise ratio, room-temperature CH3D (98% purity) and CH3D-N-2 spectra recorded with 25 cm path length (at 0.01 cm(-1) unapodized resolution) using the McMath-Pierce FTS located on Kitt Peak, Arizona, and 17 additional high quality, pure CH3D (99% purity) and CH3D-N-2 spectra recorded between 79 and 296 K with the 20.38 cm path coolable cell (at 0.0056 cm(-1) unapodized resolution) with the Bruker 125HR FTS at the Jet Propulsion Laboratory (JPL), Pasadena, California. The spectra have been fitted simultaneously applying a multispectrum nonlinear least-squares technique. In the analysis, the Lorentzian N-2-broadened half-width coefficients and the corresponding pressure-shift coefficients as well as their temperature dependences are extracted for about 400 transitions (0 <= J `' <= 19, K `' <= 16) in the perpendicular (Delta K= +/- 1) v(6) band. At 296 K, the measured N-2-broadened half-width coefficients range from 0.0209 to 0.0782 cm(-1) atm(-1) whereas the majority of the associated N-2-induced shift coefficients are negative, and the values are between -0.016 and 0.005 cm(-1) atm(-1). The temperature dependence exponents for N-2-broadened half-widths range between 0.264 and 0.924, whereas the temperature dependence coefficients for N-2-induced shifts are between 0 and 0.00011 cm(-1) atm(-1) K-1. The N-2-broadened half-width coefficients have been also calculated using a semi-classical approach based on a rigorous treatment of the active molecule as a symmetric top, a model intermolecular potential comprising both short- and long-range interactions, and exact classical trajectories. The role of the various high-order multipoles in the line-broadening at low, middle and high values of the rotational quantum number J `' has been investigated and the main features of the K-dependences analyzed. The calculations performed for 296, 240 and 190 K have allowed to deduce the half-width temperature-dependence exponents, completing the general comparison of our new experimental results with those which are available in the literature. (C) 2015 Elsevier Ltd. All rights reserved.