Subpicosecond dynamics in the excited state absorption of all-trans-β-Carotene

We have investigated the time evolution of the transient absorption spectrum of all-trans-beta-carotene in a number of solvents. In all cases we observe a loss of red and a gain of blue S-1 (2A(g)(-)) --> SN excited state absorption on a 0.3-0.4 ps time scale. To explain these observations, a model is proposed in which distorted molecules formed in S-2 (1B(u)(+)) relax back to the all-traps state in S-1 (2A(g)(-)). (C) 2002 Published by Elsevier Science B.V.