Observation of ultrafast excited-state dynamical evolution in B800 absorption band of light harvesting 2 (LH2) extracted from Rb. Sphaeroides 601

Photodynamics of two kinds of peripheral antenna complexes light harvesting 2 (LH2) of Rb. Sphaeroides 601, namely the native LH2 and B800-released LH2, where B800-BChls were partially or completely removed with different pH treatments, were studied using femtosecond pump-probe technique at different laser wavelengths. The obtained results for these samples demonstrate that under the excitation around B800 absorption band, the photoabsorption and photobleaching dynamics are caused by the direct excitation of upper excitonic levels of B850 and excited state of B800 pigments, respectively.