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The LH2 complex from Rhodopsudomonas (Rps.) palustris is unique in the heterogeneous carotenoid compositions. The dynamics of triplet excited state Carotenoids (3Car*) has been investigated by means of sub-microsecond time-resolved absorption spectroscopy both at physiological temperature (295 K) and at cryogenic temperature (77 K). Broad and asymmetric Tn←T-1 transient absorption was observed at room temperature following the photo-excitation of Car at 532 nm, which suggests the contribution from various carotenoid compositions having different numbers of conjugated C=C double bonds (Nc=c). The triplet absorption bands of different carotenoids, which superimposed at room temperature, could be clearly distinguished upon decreasing the temperature down to 77 K. At room temperature the shorter-wavelength side of the main Tn←T1 absorption band decayed rapidly to reach a spectral equilibration with a characteristic time constant of-1 μs, the same spectral dynamics, however, was not observed at 77 K. The
The LHR complex from Rhodopsudomonas (Rps.) Palustris is unique in the heterogeneous carotenoid compositions. The dynamics of triplet excited state Carotenoids (3Car *) has been investigated by means of sub-microsecond time-resolved absorption spectroscopy both at physiological temperature (295 K ) and at cryogenic temperature (77 K). Broad and asymmetric Tn ← T-1 transient absorption was observed at room temperature following the photo-excitation of Car at 532 nm, which suggests the contribution from various carotenoid compositions having different numbers of conjugated C = C double bonds (Nc = c). The triplet absorption bands of different carotenoids, which superimposed at room temperature could could be clearly distinguished upon decreasing the temperature down to 77 K. At room temperature the shorter-wavelength side of the main Tn ← T1 absorption band decayed rapidly to reach a spectral equilibration with a characteristic time constant of-1 μs, the same spectral dynamics, however, was not ob served at 77 K. The