The decay mechanism of photoexcited guanine - A nonadiabatic dynamics study

0364667 - ÚOCHB 2012 RIV US eng J - Journal Article
Barbatti, M. - Szymczak, J. J. - Aquino, A. J. A. - Nachtigallová, Dana - Lischka, H.
The decay mechanism of photoexcited guanine - A nonadiabatic dynamics study.
Journal of Chemical Physics. Roč. 134, č. 1 (2011), 14304/1-14304/5. ISSN 0021-9606. E-ISSN 1089-7690
R&D Projects: GA MŠMT LC512
Institutional research plan: CEZ:AV0Z40550506
Keywords : ab initio calculations * excited states * nucleic acids * photodynamics
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 3.333, year: 2011

Ab initio surface hopping dynamics calculations were performed for the biologically relevant tautomer of guanine in gas phase excited into the first .pi.pi.* 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 .pi.pi.* state was found in the dynamics.
Permanent Link: http://hdl.handle.net/11104/0200091