Ab initio studies of dissociation pathways on the ground- and excited-state potential energy surfaces for HFCO

摘要

Potential energy surfaces of the HFCO dissociation to H+FCO and F+HCO in the lowest three electronic states (S_0, S_1, and T_1) have been investigated with ab initio molecular orbital method at the level of the complete active space self-consistent field. An insight into the dynamics of the HFCO photodissociation at the range of 193-248 nm was provided in the present work. Radiationless transfer from S_1 to T_1 and subsequent dissociation on the T_1 surface was predicted to be the mechanism for the C-H bond cleavage, which is consistent with that proposed by experimentalists. The experimental investigations of the HFCO photodissociation suggest that the F-C bond fission also occurs as a result of intersystem crossing (ISC) from S_1 to T_1, which is not supported by the present calculations. This has been discussed in detail.