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of Siphonaxanthin in the Green Alga Codium fragile Seiji Akimoto, Tatsuya Tomo, Yukito Naitohh, Akira Otomo, Akio Murakami, Mamoru Mimuro Abstract A marine green alga, Codium fragile, exhibits a characteristic in vivo absorption band of a specific ketocarotenoid,siphonaxanthin, at 535 nm. We examined the ultrafast fluorescence kinetics by direct excitation of this band after purification of light-harvesting complex II. On the basis of a high fluorescence anisotropy (0.39) up to 1 ps and a very short lifetime (60 fs), we identified the 535 nm band as a new electronically excited state (Sx) located between the S1 and S2 states. Excited-state dynamics of the Sx state were further discussed in relation to the energy transfer processes in the complexes.  DOI:10.1021/jp071766p |