Photodissociation dynamics of CO-forming channel of methyl formate at 193 nm: a computational study

The dissociation dynamics of CO-forming channel on the ground state (S-0) of methyl formate has been studied by direct dynamics simulations and Generalised Multi-Centre Impulsive Model (GMCIM) under photon energy of 193 nm. Comparison of the simulated product-state distribution with experimental results permits us to conclude that the major forming channel of primary CO is through the conventional three-centre saddle point (TS1), which leads to CO (X-1 Sigma(+))+CH3OH ((X) over tilde (1) A') products. Besides, the photolysis wavelength dependence of product state distribution via TS1 is successfully interpreted by GMCIM, whereas the excess energy above the barrier top is treated by sudden approximation. In addition, the possibility to produce secondary CO is also considered. With the aid of phase-space theory simulation, it turns out that the most probable route to form secondary CO is via the sequential triple fragmentation due to the further decomposition of energetic HCO((X) over tilde (2) A'), which takes place on the S-0 surface of methyl formate. [GRAPHICS]