Infrared double-resonance measurements in CD3H: Vibrational energy transfer between the ν3 and ν6 Coriolis-coupled modes and between A and E symmetry species

IR pulse–probe transient absorption measurements using two CO2 lasers were performed to investigate the collisional energy transfers in CD3H. The results indicate that the vibrational energy transfer between the Coriolis-coupled ν3 and ν6 modes is very fast (≂107 s−1 Torr−1) approaching the rate of gas kinetic collisions, and occurs only between rovibrational states of the same symmetry type. Besides, evidence of a V–V transfer between the A and E species of CD3H is given, and the corresponding measured rate constant is (2.3±0.2)×105 s−1 Torr−1. It is the first time, to our knowledge, that such a V–V transfer between two different symmetry species is directly observed. The V–T, R relaxation rate constant was also determined and found to be (1.16±0.35)×103 s−1 Torr−1, in agreement with previous studies.