SOLVENT DIELECTRIC-RELAXATION PROPERTIES AND THE EXTERNAL HEAVY-ATOM EFFECT IN THE TIME-RESOLVED FLUORESCENCE QUENCHING OF ANTHRACENE BY POTASSIUM-IODIDE AND POTASSIUM THIOCYANATE IN METHANOL AND ETHANOL

Steady-state fluorescence quenching and the time-resolved fluorescence decay profiles of anthracene in the presence of iodide and thiocyanate ions in methanol and ethanol have been measured in the temperature range between 253 and 333 K. The Rips-Jortner and Onuchic theories of electron transfer are applied for data analysis. We are able to fit our experimental data with reasonable values of parameters characterizing both chemical reaction and molecular transport. Analysis of the experimental data indicates the importance of solvent dielectric relaxation properties for the fluorescence quenching. In the case of iodide ions as quencher the external heavy atom effect seems also to play an important role in the quenching process.