Vibration-vibration equilibration in laser excited CH3F and CH3F-X mixtures

Abstract

The infrared fluorescence risetime of the ν1,ν4 C–H stretching modes of CH3F has been measured in CH3F-rare-gas mixtures after pumping of the ν3 C–F stretching modes with a Q-switched CO2 laser. The pressure-dependent rate of rise was found to be 122 ± 25 msec−1 · torr−1 in pure CH3F. The effect of rare gases on this rate process was also studied and found to be consistent with a vibration-vibration filling mechanism for ν1,ν4 involving a small amount of energy transfer (≤ 75 cm−1) into the translational/rotational degrees of freedom.