Premium
FLUORESCENCE LIFETIMES OF CHLOROPHYLL a: SOLVENT, CONCENTRATION AND OXYGEN DEPENDENCE
Author(s) -
Connolly John S.,
Janzen A. Frederick,
Samuel Edward B.
Publication year - 1982
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.1751-1097.1982.tb04416.x
Subject(s) - chemistry , photochemistry , fluorescence , solvation , solvent , quenching (fluorescence) , diethyl ether , excited state , analytical chemistry (journal) , organic chemistry , physics , quantum mechanics , nuclear physics
Fluorescence lifetimes (τ f ) of chlorophyll a (Chi a ) have been measured by the single‐photon‐counting technique over a wide range of concentrations (˜10 ‐7 ˜10 ‐4 M ) in deoxygenated pyridine, diethyl ether, toluene and methanol. At pigment concentrations ˜1 μ M , reabsorption of fluorescence induces significant artifacts on measured values of τ f which are dependent on detection wavelength and the specific geometry of the experiment. There is a clear dependence of τ f on the nature and degree of solvation, including both coordination of the central magnesium and hydrogen‐bonding of the solvent (viz. alcohols) to the macrocycle. Quenching of the excited singlet state by molecular oxygen was measured quantitatively in ether, and a bimolecular rate constant markedly slower than the diffusion‐controlled limit was obtained.