title: Ultrafast dynamics of all-trans--carotene explored by resonant and nonresonant photoexcitations.
abstract: Excitation energy dependence of transmittance change has been investigated in -carotene. The signal induced by nonresonant excitation is ascribed to the ac Stark effect and the two-photon absorption of the excitation and probe pulses in three-level systems. The ultrafast response following resonant excitation is assigned to the two-photon absorption and the transient absorption of the photogenerated S(2) state with a lifetime of 150 fs. The long-debated S(2)-S(1) relaxation in beta-carotene can be explained by a two-state model (S(2), S(1)) without involving any intermediate states.
authors.affiliation: Department of Physics, Graduate School of Science, Tohoku University, Aramaki-aza-aoba, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Kosumi
authors.forename: M
authors.initials: M
authors.lastname: Komukai
authors.forename: H
authors.initials: H
authors.lastname: Hashimoto
authors.forename: M
authors.initials: M
authors.lastname: Yoshizawa
mesh_terms: D010777:Photochemistry; D013816:Thermodynamics; D019207:beta Carotene / Q000737:chemistry*
chemical_list: D019207:beta Carotene