MIN ZHANG, JIANQIANG MA, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104; HAI-LUNG DAI, Department of Chemistry, Temple University, Philadelphia, PA 19122.
The collision relaxation cross section of highly vibrationally excited SO2 at energies around 45,000 cm\-1, which is just below the dissociation limit, has been measured for several \testitsingle, highly vibrationally excited levels. The measurement was conducted on rotationally cooled SO2 in supersonic jet condition using quantum beat spectroscopy. Quantum beat in laser induced fluorescence from the C state is due to vibronic coupling between zero-order rovibronic levels of C and X states and can be analyzed to give the decay rate constants of the high vibrational levels of the X state. It is found that the collision relaxation cross section of the single highly vibrationally excited level shows a strong correlation with the corresponding vibronic coupling matrix element, likely reflecting that the part of the vibrational character of the single high vibrational level that gives a larger coupling with the C state also provide a stronger transition dipole moment contribution to its collision relaxation.