Isotope effects in the ultrafast photodissociation of acetone 3s Rydberg state excited at 195 nm

Abstract

The deuterium isotope effect in the photodissociation of acetone S 2 state was studied using femtosecond pump–probe ionization spectroscopy. The transients obtained for both isotopomers can be well described by the same mechanism in which the primary dissociation occurs on the S 1 surface. Substantial isotope effects were observed in every stage of the reaction. Our results indicted that upon full deuteration the initial-state decay from S 2 to S 1 slows down by a factor of three, the subsequent adiabatic dissociation on the S 1 surface slows down by a factor of four, and the secondary dissociation slows down by a factor of ∼1.6.