Relaxation kinetics on the first excited singlet state of SO2 from time resolved emission spectra

The relaxation kinetics on the first excited singlet state (1A2) of SO2 have been studied from time-resolved emission spectra in the 300–450 nm region. Two rovibronic levels belonging to the elements E-band and the 1A2 (0,8,1) level, which are located above and below the origin of the 1B1 state, respectively, were excited to investigate the role of the 1B1 state on the relaxation kinetics. Direct emissions from the laser excited rovibronic levels in the 1A2 state and direct intersystem crossing between the 1A2(0,8,1) and 3B1 states were observed and revised relaxation kinetic schemes are proposed.