Relaxation kinetics on the first excited state of SO2

The relaxation kinetics on the first singlet state (A∼'1A2) of SO2 have been studied from time resolved emission spectra in the 300-450 nm region. When a few rotational levels belonging to the A∼1A2 state were populated by a narrow bandwidth laser, both the fluorescence from the A∼1A2 state and the phosphorescence from the a∼3B1 state were observed. The fluorescence signal showed fast and slow decay components. The radiative lifetimes and apparent quenching rate constants were obtained from the fast component analysis. Kinetic simulations of the emission profiles were done to obtain the magnitudes of intersystem crossing and revibronic relaxation rate constants. Also, vibronic relaxation among the Clements bands of SO2 molecule has been observed from detailed time-resolved fluorescence spectra. (author)