Photodissociation Dynamics of Benzaldehyde-d₅ at 205 nm:The H Atom Production Channel

摘要

Photodissociation dynamics of benzaldehyde- d _(5) (C_(6)D_(5)CHO) at 205 nm was investigated by measuring laser-induced fluorescence spectra of fragment H atoms. From the Doppler-broadened spectra, center-of-mass translational energy release into the C_(6)D_(5)CO + H channel was obtained as 68.8 ± 5.8 kJ/mol with the absolute quantum yield, 0.17 ± 0.03. The observed translational energy was successfully estimated from two-dimensional potential energy surfaces along the C–H dissociation coordinate and the CCO bent angle and the out-of-plane H angle, respectively calculated at the B3LYP/cc-pVDZ level. The dissociation of H should take place along the triplet surface via intersystem crossing from S_(1) after internal conversion from the initially excited S_(3) state and on the triplet surface, the dissociation proceeds along the CCO bent-linear-bent configuration with H being planar to nonplanar pathway.