Influence of temperature on quenching of fluorescence in compounds of the coumarin series

A study has been made of the influence of temperature on the quantum yield of fluorescence of 3,4-benzocoumarin in ethanol or n-hexane, in the temperature interval 77–300 K. A mechanism of fluorescence quenching is proposed, consisting of thermal activation of intercombination conversion between neighboring energy levels that differ in orbital nature.Poltava Branch, Academy of Sciences of Engineering Cybernetics of the Ukraine, 3 Koval' Street, Poltava 314601, Ukraine. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 32, No. 4, pp. 247–250, July–August, 1996. Original article submitted September 26, 1995.