Transfer-State Population in Liquid Scintillators

A parameter, $n_e$ , which represents the number of primary excited solvent molecules from which energy can be transferred to the scintillator, may be determined by studying fluorescence under high‐energy and ultraviolet excitations. The temperature variation of $n_e$ was measured over a range of 200°C and was found to be considerable for high‐energy excitation. This variation is attributed to changes in intermolecular coupling. Following ideas of Magee and Platzman, we assume the (bulk modulus)^1/3 as a measure of this coupling. The experimental results show good agreement with the theory. Study of different solutes reveals that $n_e$ is made up of two factors only one of which is temperature dependent.