Abstract
The fragment HCO, produced from acetaldehyde by photolysis at 300 nm, was detected by laser-induced fluorescence of B̃ 2 A′-X̃ 2 A′ transitions. The fluorescence lifetimes of the HCO B̃ state decrease rapidly as the photolysis energy increases, indicating strong predissociation of the B̃ state. The radiative lifetimes of B̃ are in the range 70-90 ns for (0, 0, 0) K′ = 0 states and 42-50 ns for K′ = 1 states. For all measured vibrational levels, the K′ = 1 states have smaller average lifetimes than the K′ = 0 states. Correction over individual lifetimes is necessary to obtain the state population if the B̃ state is excited. The state B̃ (0, 1, 0) has a shorter average lifetime than the states (1, 0, 0) and (0, 0, 2), despite having a lower energy. © 1994.