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The dependence of quinine fluorescence quenching on ionic strength
Author(s) -
Verity Bruce,
Bigger Stephen W.
Publication year - 1996
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1996)28:12<919::aid-kin9>3.0.co;2-q
Subject(s) - chemistry , quenching (fluorescence) , ionic strength , reaction rate constant , diffusion , fluorescence , salt (chemistry) , chloride , ion , ionic bonding , steady state (chemistry) , photochemistry , kinetics , analytical chemistry (journal) , thermodynamics , aqueous solution , chromatography , organic chemistry , physics , quantum mechanics
The Stern‐Volmer constant for the quenching of quinine fluorescence by chloride ions has been found to be markedly dependent on acid concentration. Steady‐state and time‐resolved fluorescence measurements under different acid and salt concentrations have further shown that the decrease in quenching arises from the influence of increasing ionic strength on the diffusion‐controlled rate constant for the bimolecular quenching process. Two possible mechanisms for this dependence are discussed: a decrease in the intrinsic rate constant for the reaction due to the kinetic salt effect, and a decrease in the effective encounter distance due to screening of the charges on the reactants. © 1996 John Wiley & Sons, Inc.