Conical for stepwise, glancing for concerted: The role of the excited state topology in three-body dissociation of sym-triazine

V.A. Mozhayskiy, J.D. Savee, J.E. Mann, R.E. Continetti, and A.I. Krylov
J. Phys. Chem. A 112, 12345–12354 (2008)

The highly debated three-body dissociation of sym-triazine to three HCN products has been investigated by translational spectroscopy and high-level ab initio calculations. Dissociation was induced by charge exchange between the sym-triazine radical cation and cesium. Calculated state energies and electronic couplings suggest that sym-triazine is produced in the 3s Rydberg and n,pi* manifolds. Analysis of the topology of these manifolds along with momentum correlation in the dissociation products suggest that the 3s Rydberg manifold characterized by a conical intersection of two potential energy surfaces leads to stepwise dissociation, while the n,pi* manifold consisting of a four-fold glancing intersection leads to a symmetric concerted reaction.

Download this paper (PDF)

Related Research

Computational studies of electronically excited and open-shell species: Jahn-Teller systems, radicals, diradicals and triradicals