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SPECTRAL INHOMOGENEITY OF THE LIGHT‐HARVESTING ANTENNA OF Rhodospirillum rubrum PROBED BY TRIPLET‐MINUS‐SINGLET SPECTROSCOPY AND SINGLET‐TRIPLET ANNIHILATION AT LOW TEMPERATURES
Author(s) -
Mourik Frank van,
Visscher Kees J.,
Mulder Jan M.,
Grondelle Rienk van
Publication year - 1993
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1993.tb02248.x
Subject(s) - annihilation , rhodospirillum rubrum , singlet state , photochemistry , quenching (fluorescence) , spectroscopy , spectral line , fluorescence , chemistry , antenna (radio) , molecular physics , physics , atomic physics , excited state , nuclear magnetic resonance , optics , particle physics , enzyme , telecommunications , quantum mechanics , astronomy , computer science
–Triplet‐minus‐singlet (T‐S) spectra and singlet‐triplet annihilation was measured on Rhodospirillum rub‐rum chromatophores at low temperatures (4–77K). The T‐S spectrum of the LH‐1 antenna was dependent on the wavelength of excitation and thus indicative of site‐inhomogeneous broadening. The data cannot be understood adequately using the two pigment pool model (B880 + B896) but, in contrast, support a model for LH‐1, in which the spectral properties are determined by site‐inhomogeneous broadening. Consequently, the 4 K antenna domain for singlet‐triplet annihilation in LH‐1 is rather small. If the temperature is raised to 77 K the annihilation domain increases, and a fit of the fluorescence quenching and triplet yield data suggests that at 77 K the connectivity is between the extreme cases of the “lake” and the isolated “puddles” models. The implications of the observed antenna inhomogeneity on low temperature annihilation and fluorescence measurements are discussed.