An ab initio study on photodissociation of acetone

CH3COCH3 photodissociation was investigated using the CASSCF energy gradient techniques. After the acetone molecules are populated in the S1 state by photoexcitation at 193 nm, the intersystem crossing to the T1 surface is the most probable pathway for CH3COCH3 (S1) deactivation. Relaxing to the T1 state, CH3COCH3 (T1) first dissociates into CH3CO (2A′) and CH3 (2A2″) products, and then the CH3CO (2A′) formed further easily dissociates into CH3 and CO. This stepwise mechanism is consistent with numerous experiments.