Fluorescence quenching by weak quenchers

Abstract

The quenching of the fluorescence of anthracene in benzene by ethyl iodide, allyl bromide, chloroform, benzoyl peroxide, P - toluene sulphonyl chloride and P - bromo-diphenyl has been measured with a sensitive fluorimeter constructed for the purpose. That quenching was not due to absorption of either the exciting or fluorescent light was shown by absorption spectra measurements. Quenching is considered to be controlled by the number of activated collisions in solution and by the free energy of formation of encounters. Factors which influence the number and effectiveness of collisions are discussed.