THE FLUORESCENCE OF ADENINE. THE EFFECTS OF SOLVENT AND TEMPERATURE ON THE QUANTUM YIELD

Abstract— To investigate the mechanism of the solvent and thermal quenching of fluorescence, the absolute fluorescence quantum yield of adenine has been determined in several alcoholic glasses as a function of the concentration (10^-5-10^-4M) and temperature (77°-298°K). The yield is independent of the concentration but increases with decreasing temperature and increasing bulk cohesion and rigidity of the solvent.
The environmental effects on the yield are attributed to radiationless electronic relaxation processes caused by solute-solvent interaction. Increasing the temperature and decreasing the intra-solvent cohesion cause increases in the interaction and therefore accelerate the relaxation. The rate determining step behaves like a diffusion in the limit of low viscosity.