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PHYSICAL AND PHOTOCHEMICAL PROPERTIES OF A FLUORESCENT CHLOROPHYLL COLLOID
Author(s) -
Bannister T. T.,
Bernardini J. E.
Publication year - 1963
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.1751-1097.1963.tb08911.x
Subject(s) - colloid , molar absorptivity , fluorescence , chemistry , quantum yield , yield (engineering) , absorption (acoustics) , chlorophyll a , photochemistry , chlorophyll fluorescence , chlorophyll , substrate (aquarium) , analytical chemistry (journal) , chromatography , materials science , organic chemistry , optics , biochemistry , physics , oceanography , metallurgy , composite material , geology
— A fluorescent colloid of chlorophyll a , of which some qualitative properties were noted by Krasnovsky and Brin (11) , has been quantitatively characterized. The colloid is formed in neutral PO 4 buffer containing 0 1 to 8.0% Tween 20, and is stable in darkness. The extinction coefficient is 7.8 × 10 4 1. mole cm ‐1 at the red absorption peak (668 mμ), the yield of fluorescence is ˜ 0.25, and the yield of photoautooxidative bleaching is ˜ 2 times 10 ‐4 . The colloid sensitizes the autooxidation of paratoluenediamine with a yield of ˜0.01 to ˜0.3 depending on light intensity and substrate concentration. The yield is independent of detergent and chlorophyll concentrations. In all respects—except the dependence of yield on illumination—the colloid appears to be physically and photochemically equivalent to dissolved chlorophyll, as known in dilute solutions in organic solvents. The light dependence—the yield is inversely proportional to the cube root of absorbed intensity—could be due to a bimolecular back reaction of a chlorophyll or substrate derivative.