Infrared laser double resonance study of vibrational energy exchange between 12CH3F and 13CH3F

Laser–laser infrared double resonance has been used to study energy transfer from the 12CH3F to the 13CH3F isotopic species. The 12CH3F ν3 mode was pumped by a Q-switched 9.6 μ CO2 laser operating on the P (20) line, while the 13CH3F ν3 absorption was monitored by a cw CO2 laser operating on the P (32) 9.6 μ transition. Equilibration of the ν3 modes in the two isotopes occurs in approximately six gas kinetic collisions. Evidence for a somewhat slower equilibration of the ν6 modes in the two isotopes has also been observed. These results give further support to the idea that ladder climbing collisions can lead to a rapid redistribution of energy into high lying states of polyatomic molecules.