Ultrafast dynamics of all-trans--carotene explored by resonant and nonresonant photoexcitations.
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.
Kosumi
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D
Department of Physics, Graduate School of Science, Tohoku University, Aramaki-aza-aoba, Aoba-ku, Sendai 980-8578, Japan.
Komukai
M
M
Hashimoto
H
H
Yoshizawa
M
M
D010777:Photochemistry; D013816:Thermodynamics; D019207:beta Carotene / Q000737:chemistry*
D019207:beta Carotene