Temperature dependences of self- and N2-broadened line-shape parameters in the ν3 and ν5 bands of 12CH3D: Measurements and calculations

- Temperature dependences of N2-widths and shifts in the ν3 and ν5 bands of 12CH3D.
- Multispectrum analysis of 23 high resolution FTS spectra recorded in the 75-296 K range.
- 12CH3D-N2 line mixing coefficients using the off-diagonal relaxation matrix formalism.
- Comparison of measurements with semi-classical calculations.
- Measurements of line positions and intensities for transitions in the ν3 and ν5 bands.

This paper presents the results of a spectroscopic line shape study of self- and nitrogen-broadened 12CH3D transitions in the ν3 and ν5 bands in the Triad region. We combined five pure gas spectra with eighteen spectra of lean mixtures of 12CH3D and nitrogen, all recorded with a Bruker IFS-125 HR Fourier transform spectrometer. The spectra have been analyzed simultaneously using a multispectrum nonlinear least squares fitting technique. N2-broadened line parameters for 184 transitions in the ν3 band and 205 transitions in the ν5 band were measured. In addition, line positions and line intensities were measured for 168 transitions in the ν3 band and 214 transitions in the ν5 band. We have observed 10 instances of weak line mixing corresponding to K″=3 A1 or A2 transitions. Comparisons were made for the N2-broadening coefficients and associated temperature exponents with corresponding values calculated using a semi-classical Robert Bonamy type formalism that involved an inter-molecular potential with terms corresponding to short- and long-range interactions, and exact classical molecular trajectories. The theoretical N2-broadened coefficients are overestimated for high J values, but are in good agreement with the experimental values for small and middle range J values.