Abstract

Femtosecond studies using laser-induced fluorescence and multiphoton ionization (MPI)[1] have lead to considerable progress in understanding small molecule gas phase photodissociation dynamics. In this letter we describe experiments that extend these studies to shorter wavelengths. This makes it possible to investigate molecules that absorb weakly in the visible or near UV, which is often the case for many small molecules. We have generated femtosecond deep UV (near 205 nm) pulses, which have been used to directly measure the excited state lifetime for the predissociative S₃ state of CS₂ and to study the two-photon state of NO at 102 nm using time-resolved MPI. The lifetime measured for CS₂ is compared with several indirectly measured values, and the pressure dependence observed for the decay times for NO was measured and analyzed to obtain both the unimolecular lifetime and bimolecular rate constant.

© 1994 Optical Society of America