title: Excited-state dynamics of overlapped optically-allowed 1B(u) and optically-forbidden 1B(u) or 3A(g) vibronic levels of carotenoids: possible roles in the light-harvesting function.
abstract: The unique excited-state properties of the overlapped (diabatic) optically-allowed 1B(u) (+) and the optically-forbidden 1B(u) (-) or 3A(g) (-) vibronic levels close to conical intersection ('the diabatic pair') are summarized: Pump-probe spectroscopy after selective excitation with approximately 100 fs pulses of all-trans carotenoids (Cars) in nonpolar solvent identified a symmetry selection rule in the diabatic electronic mixing and diabatic internal conversion, i.e., '1B(u) (+)-to-1B(u) (-) is allowed but 1B(u) (+)-to-3A(g) (-) is forbidden'. On the other hand, pump-probe spectroscopy after coherent excitation with approximately 30 fs of all-trans Cars in THF generated stimulated emission with quantum beat, consisting of the long-lived coherent diabatic cross term and a pair of short-lived incoherent terms.
authors.affiliation: Kwansei Gakuin University, Sanda, Hyogo, Japan. ykoyama@kwansei.ac.jp <ykoyama@kwansei.ac.jp>
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Koyama
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kakitani
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miki
authors.forename: Rebecca
authors.initials: R
authors.lastname: Christiana
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Nagae
mesh_terms: D002338:Carotenoids / Q000737:chemistry* / Q000378:metabolism; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory; D013053:Spectrophotometry; D013816:Thermodynamics
chemical_list: D045342:Light-Harvesting Protein Complexes; D002338:Carotenoids