title: The decay mechanism of photoexcited guanine - a nonadiabatic dynamics study.
abstract: Ab initio surface hopping dynamics calculations were performed for the biologically relevant tautomer of guanine in gas phase excited into the first ππ∗ state. The results show that the complete population of UV-excited molecules returns to the ground state following an exponential decay within ∼220 fs. This value is in good agreement with the experimentally obtained decay times of 148 and 360 fs. No fraction of the population remains trapped in the excited states. The internal conversion occurs in the ππ∗ state at two related types of conical intersections strongly puckered at the C2 atom. Only a small population of about 5% following an alternative pathway via a nπ∗ state was found in the dynamics.
authors.affiliation: Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany. barbatti@mpi-muelheim.mpg.de
authors.forename: Mario
authors.initials: M
authors.lastname: Barbatti
authors.forename: Jaroslaw J
authors.initials: JJ
authors.lastname: Szymczak
authors.forename: Adélia J A
authors.initials: AJ
authors.lastname: Aquino
authors.forename: Dana
authors.initials: D
authors.lastname: Nachtigallová
authors.forename: Hans
authors.initials: H
authors.lastname: Lischka
mesh_terms: D006147:Guanine / Q000737:chemistry*; D011789:Quantum Theory; D013499:Surface Properties; D014466:Ultraviolet Rays
chemical_list: D006147:Guanine