Femtosecond stimulated raman spectroscopy of the dark S1 excited state of carotenoid in photosynthetic light harvesting complex

Abstract

Vibrational dynamics of the excited state in the lightharvesting complex (LH1) have been investigated by femtosecond stimulated Raman spectroscopy (FSRS). The native and reconstituted LH1 complexes have same dynamics. The v1 (C=C stretching) vibrational mode of spirilloxanthin in LH1 shows ultrafast high-frequency shift in the S1 excited state with a time constant of 0.3 ps. It is assigned to the vibrational relaxation of the S1 state following the internal conversion from the photoexcited S2 state. © by Pawel Pomorski and Polish Biochemical Society 2009.