Steady state and time resolved methods of fluorescence quenching of three coumarin dyes using S-V plots

Abstract

Studies of steady state and time resolved methods of fluorescence quenching of excitation energy of three coumarin dyes by aniline were carried out in toluene solvent only to understand the role of diffusion in the quenching mechanism. The coumarin dyes (dye1, dye2 and dye3) were excited directly by UV radiation of 350 nm and probabilities of quenching per encounter <i>p</i> (or <i>p</i>') were determined in the toluene solvent. Further, the activation energy <i>E</i>'<i>a</i> (or<i> E</i>'<i>_a</i>) of quenching was determined using the literature values of activation energy of diffusion <i>E_d</i> and the experimentally determined values of <i>p</i>

(or <i>p</i>'). Magnitudes of <i>p</i> (or <i>p</i>') as well as the values of<i> E_a </i>(or<i> E</i>'<i>_a</i>) suggest that the quenching reaction is predominantly controlled by material diffusion.