| The collisional dynamics of highly vibrationally excited SO2 and NO2 have been explored. Kinetic quantum beat spectroscopy has been used to measure the state-resolved collision-induced depopulation and pure dephasing cross sections of highly vibrationally excited SO2 by coherent laser excitation in a supersonic jet. In addition, the modeling of the V-T energy transfer channel has been constructed based on the previous time-resolved Fourier transform emission spectroscopy results of highly vibrationally excited NO2 colliding with inert gases (He, Ne, Ar, Kr, Xe).;First, a model is proposed to describe the collision-induced pure dephasing in the coherent system and is used to measure the pure dephasing cross section of a pair of eigenstates originating from vibronic coupling between optically "bright" and "dark" levels of SO2 with 44877.52cm-1 above the zero energy. Second, with this modified description for quantum beat spectroscopy, more than ten state-resolved highly vibrationally excited levels have been examined within three vibrational levels, (210), (140) and (132), in the C˜1 B2 state. The measured collision-induced depopulation cross section of highly vibrationally excited SO2 with CO has a positive dependence on the vibronic coupling matrix element between the coupled "bright" and "dark" levels, which can be understood by the V-E energy transfer for such energized molecules. Finally, our calculation shows that the long range interaction through the dipole-moment mediated transitions between eigenstates should be responsible for the large energy loss per collision of highly excited NO2 with inert gases measured by previous experiments in time-resolved Fourier transform spectroscopy. This calculation, combined with the prior measured depopulation cross sections, shows that the long range interaction plays an import role in the collisional dynamics of highly vibrationally excited molecules. |
