Semi-empirical calculations of line-shape parameters and their temperature dependences for parallel bands of monodeuterated methane perturbed by nitrogen

Theoretical nitrogen-pressure broadening and shift coefficients as well as their temperature-dependence characteristics for 12CH3D (J, K) lines in the parallel (ΔK=0) ν3 band are calculated by a semi-empirical approach based on analytical Anderson-type expressions corrected to account for the real curved trajectories. The parameters of the correction factor are adjusted on some recent experimental data for room-temperature line-broadening coefficients, and the unknown CH3D polarizability in the excited vibrational state is determined from a few measurements of room-temperature line-shifts. After validation by comparison with a set of measured values from the literature, this approach is employed for massive calculations of line-shape parameters for enlarged ranges of rotational quantum numbers (0 ≤ J ≤ 70, 0 ≤ K ≤ 20) requested by atmospheric/astrophysical applications and spectroscopic databases. The temperature-dependence characteristics are obtained for the range 200-400 K recommended for HITRAN. Given the negligible vibrational dependence of CH3D line-widths, our calculated broadening coefficients and their temperature-dependence exponents can be also used for other CH3D-N2 parallel bands.