Vibronic relaxation among the Clements bands of SO2 from the E-band excitation

Vibronic relaxation among the Clements bands of SO2 molecule has been studi ed from time-resolved fluorescence spectra in the 300-350 nm region. The K' = 6, J' = 7 level of the Clements E-band was populated at 32 812.8 cm(-1), and detailed time-resolved fluorescence spectra for the period 0-160 ns we re obtained. Following the fast decay of the laser excited level, weak emis sions from Clements A-F bands appeared almost simultaneously. The simultane ous appearance of many Clements bands was attributed to fast rovibronic rel axation of the laser excited molecules among the dark levels. It was also f ound that the broad apparent continuum emission following the direct fluore scence showed different decay rates at different wavelengths, but the decay rates of the emissions for lambda > 350 nm were virtually identical. Based on the wavelength dependence of the decay rates, the apparent continuum em issions were ascribed to the emissions from the rovibronically dispersed hy brid bright states and the low-lying rovibrational levels of the (A) over t ilde(1)A(2) state generated by collisional relaxation of the laser-excited level.