Dinamika Tahapan Tereksitasi Singlet pada Karotenoid

Abstract

Singlet excited states of carotenoid play crucial roles in the carotenoid-to-bacteriochlorophyll singlet-energy transfer reactions in photoshynthetic organisms. It had been well accepted that there were two low-lying singlet excited states of carotenoid, i.e. 11Bu+ and 21Ag-. Recently, 11Bu- and 31Ag- states have been discovered as new singlet of carotenoid. Involvement of absorption, fluorescence, resonance-Raman-excitation profiles and transient absorption spectroscopy in order to elucidate singlet-excited states of some typical carotenoids are summarized. The prospects of carotenoid-to-bacteriochlorophyll singlet-energy transfer via carotenoid singlet excited states are also included. On the bases of the energies and the lifetime of singlet excited states of carotenoids in solution and bound to the light-harvesting complexes, vibrational relaxation, internal conversion, and the dynamics of the light harvesting function are discussed with emphasis on 11Bu+, 21Ag-, 11Bu- and 31Ag- states