Some effects of temperature on fluorescence for pure toluene and liquid scintillator

The fluorescence maxima of pure toluene shift to longer wavelengths at lower temperatures. At room temperature the wavelength of the fluorescence maximum of pure toluene is longer than that in hexane. The red shift suggests that the fluorescence emission from excimer of toluene is promoted at lower temperatures. The fluorescence intensity from pure toluene and PPO solution in toluene increases with decreasing temperature. The differential pulse-height distributions from α- and β-particles shift to higher pulse-height with decreasing temperature. It is proposed that the phenomena are explained by the promoted solvent excimer fluorescence at lower temperatures.