Abstract

Carotenoids serve important functions in photo synthetic organisms: as structural components of pigment-protein complexes, accessory light-harvesting pigments and photoprotective agents. Elucidation of the role(s) of the lowest excited singlet states of carotenoids, in particular, of the (optically „dark“) state 2A_g^- (S₁) in light harvesting and excess energy dissipation is a field of intense current research interest. Two-photon absorption (TPA) of carotenoids detected by (bacterio)chlorophyll, (B)Chl, fluorescence (following excitation energy transfer, EET) can be used to localize the (optically “dark”) 2A_g^- (S₁) state of relevant carotenoids in photosynthetic pigment-protein complexes (Fig. 1, cf. also [1]).

© 2007 IEEE