title: The interplay between ππ*/nπ* excited states in gas-phase thymine: a quantum dynamical study.
abstract: A quantum mechanical study of the interplay between the bright ππ*(S(π)) and the dark nπ*(S(n)) excited states of thymine in the gas phase is reported. TD-PBE0 calculations indicate that within a relevant region of the S(π) surface, connecting the Franck-Condon point with the planar and non-planar S(π) plateau, S(π) and S(n) are almost isoenergetic and that a S(π)→S(n) population transfer is therefore likely. This latter process has been studied by two complementary quantum dynamical approaches, a three-dimensional anharmonic (quartic) model, and a full-dimensional harmonic linear vibronic coupling model. Although providing slightly different quantitative indications, both approaches predict a very fast and effective S(π)→S(n) population transfer: already at 50 fs the S(n) state is significantly populated (20-40%) and this population persists or even increases on a longer time scale.
authors.affiliation: Scuola Normale Superiore, Piazza dei Cavalieri, 7 I-56126 Pisa, Italy.
authors.forename: David
authors.initials: D
authors.lastname: Picconi
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Barone
authors.forename: Alessandro
authors.initials: A
authors.lastname: Lami
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Santoro
authors.forename: Roberto
authors.initials: R
authors.lastname: Improta
mesh_terms: D005740:Gases / Q000737:chemistry*; D008958:Models, Molecular; D011789:Quantum Theory; D013816:Thermodynamics; D013941:Thymine / Q000737:chemistry*
chemical_list: D005740:Gases; D013941:Thymine