ELECTRON-TRANSFER REACTIONS STUDIED THROUGH THE TRANSIENT EFFECT IN FLUORESCENCE QUENCHING

Fluorescence quenching by high concentration (>0.1M) of quencher cause s nonexponential decay of fluorescence (the transient effect). Electro n transfer reactions were studied by measuring the transient effect in fluorescence quenching. The rate parameters J(0) (the transfer integr al at a donor-acceptor separation of 6 Angstrom and beta (attenuation coefficient of the transfer integral) were determined by fitting the c alculated decay curves to the measured ones. The distribution Y(r) of electron transfer distance is expressed in terms of the distance depen dence of the rate constant, the quencher distribution function and the fluorescence decay curve. Y(r) was calculated using the values of J(0 ) and beta obtained experimentally. Finally, the distribution Y(r) was used to calculate the yield of free ions which are formed after charg e separation reactions.