Degenerate four-wave mixing spectroscopy of jet-cooled S02 via the C̃-X̃ transition

The C 1132 ← X̃1ʹA, transition of jet-cooled SO2 has been observed by degenerate four-wave mixing (DFWM) spectroscopy. Under the condition with a high input laser power, the DFWM intensity was proportional to the laser power and the DFWM spectrum represented the absorption spectrum. The relative fluorescence quantum yield was obtained by comparing the DFWM spectrum with the LIF spectrum. The vibronic dependence of the quantum yield agreed well with that of the fluorescence lifetime. It was found that the predissociation rate of the vibronic levels involving anti-symmetric stretching vibration is much faster than others.