Three-body photodissociation of 1,3,5-triazine

The three-body dissociation of 1,3,5-triazine (H3C3N3 --> 3HCN) has been studied by molecular beam photofragment translational spectroscopy following excitation at 308, 295, 285, 275, 248, and 193 nm. The analysis of the measured translational energy distributions of the HCN photofragments has shown that the dissociation mechanism is not, as previously suggested, a symmetric (or synchronous) three-body process but rather is a two-step concerted process, where concerted refers to correlation between the asymptotic velocity vectors of the three ejected HCN fragments. Furthermore, there is evidence that the initially excited electronic state ((1)E '', (1)A(2)) is deactivated by radiationless processes (internal conversion/intersystem crossing) to a lower electronic and finally dissociative state which is, according to symmetry correlation, the electronic ground state (electronic predissociation).