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

Abstract

We have investigated the time evolution of the transient absorption spectrum of all- trans-β-carotene in a number of solvents. In all cases we observe a loss of red and a gain of blue S 1 (2 A g −)→ S N 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 (1 B u +) relax back to the all- trans state in S 1 (2 A g −) .