Carotenoid-to-Chlorophyll Energy Transfer in Recombinant Major Light-Harvesting Complex (LHCII) of Higher Plants. I. Femtosecond Transient Absorption Measurements

The energy transfer kinetics from carotenoids to chlorophylls and among chlorophylls has been measured by femtosecond transient absorption kinetics in a monomeric unit of the major light-harvesting complex (LHCII) from higher plants. The samples were reconstituted complexes with different carotenoid contents. The kinetics was measured both in the carotenoid absorption region and in the chlorophyll Q y region using two different excitation wavelengths suitable for selective excitation of the carotenoids. Analysis of the data shows that the overwhelming part of the energy transfer from the carotenoids occurs directly from the initially excited S 2 state of the carotenoids. Only a small part (