Photodissociation pathways and conical intersections in the low-lying electronic states of SiH+2

Mort, Steve P.; Jennings, Neville A.; Balint-Kurti, Gabriel G.; Hirst, David M.
December 1994
Journal of Chemical Physics;12/15/1994, Vol. 101 Issue 12, p10576
Academic Journal
Potential energy surfaces are computed for the four lowest electronic states of SiH+2. The surfaces provide the data necessary for the discussion of the competitive photodissociation of SiH+2 to yield either SiH+ or Si+. The study has resulted in the ‘‘discovery’’ of a new conical intersection involving the ground state potential energy surface and a surface which had not previously been thought to lie at sufficiently low energies to be of interest in the photodissociation dynamics of the system. The three important conical intersections and their role in the photodissociation dynamics are discussed. Likely pathways leading from the photoexcited state created in the spectroscopic experiments to the observed SiH+ and Si+ ionic fragments are described. The ion, after initial excitation, has A 2A‘ or odd symmetry and is thought to convert to a lower-lying even symmetry state (2A’) by making a transition from the upper- to the lower-half of a 2Π state through the mediation of a Renner–Teller coupling mechanism. The effect of the conical intersection on the strength and qualitative nature of the coupling between these two surfaces is examined. © 1994 American Institute of Physics.


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