SINGLET EXCITED-STATES AND THE LIGHT-HARVESTING FUNCTION OF CAROTENOIDS IN BACTERIAL PHOTOSYNTHESIS

The recent results of stationary-state and time-resolved absorption, f luorescence and Raman spectroscopies of some typical carotenoids are s ummarized. Theoretical analyses of carotenoid singlet states and of ca rotenoid-to-bacteriochlorophyll singlet-energy transfer are also inclu ded. On the bases of the energies, the lifetimes and other properties of singlet excited states of the carotenoids in solution and bound to the light-harvesting complexes, the energetics and the dynamics of the light-harvesting function in purple photosynthetic bacteria are discu ssed with emphasis on the 2A(g)(-) and B-u(+) states.