Femtosecond induced susceptibility change due to a two-photon population grating in carotenoid solutions

Organic materials with /spl pi/-conjugated electron systems attract much attention because of their large optical nonlinearities. One of the organic molecules with an extended /spl pi/-electron structure is carotene. Moreover, excited states of carotenoids play crucial roles in the primary processes of photosynthesis. Information on electronic energy levels of carotenoids is essential to understand the mechanism of their harvesting function in photosynthetic systems. In the present study, we have investigated femtosecond dynamics of optical nonlinearity in /spl beta/,/spl beta/-carotene (/spl beta/-carotene) solutions by means of an optical heterodyne-detected optical Kerr effect (OHD-OKE) technique.