Laser fluorescence study of vibrational energy transfer in CH3Cl

Abstract

A laser induced infrared fluorescence technique has been used to measure both vibration to vibration and vibration to translation/rotation energy transfer rates in CH₃Cl. The $\mathrm{V‐T/R}$ rates were measured using H₂, D₂, CH₄, and rare gases as collision partners. Qualitative comparison of these data with $\mathrm{V\; \to \; T}$ and $\mathrm{V\; \to \; R}$ theories indicates that the $\mathrm{V\; \to \; T}$ mechanism dominates for collisions with small reduced masses while the $\mathrm{V\; \to \; R}$ mechanism dominates for collisions with large reduced masses. The V–V rate equilibrating the ν₆ and ν₃ modes was measured as a function of CH₃Cl pressure and was found to be $\text{76\hspace{0.17em}}{\mathrm{msec}}^{\text{−1}}·{\mathrm{torr}}^{\text{−1}}$ . A lower limit was also obtained for the rate of V–V energy transfer from states near 1000 cm⁻¹ to high lying states near 3000 cm⁻¹.