Collisional broadening of rotational lines in the simulated Raman pentad Q-branch of CD4.

Self-and argon-broadening coefficients are reported for a number of Raman Q-branch transitions in the ν₁ and ν₂+ν₄ bands of ¹²CD₄ at room temperature (296K). The coefficients display a variation with j and with Cⁿ (symmetry species A, E, F) that is essentially independent of collision partner and which is similar to the j- and Cⁿ-dependence found in previous measurements of the i.r. line-broadening coefficients. The rotationally inelastic collision rates previously measured by Foy et al. for ¹³CD₄(υ₄ = 0, 1) in collision with ¹³CD₄ or Ar account for only a part of the Raman broadening rate, suggesting possibly significant contributions to the linewidths from efficient V-V transfer or elastic dephasing collisions.