TEMPERATURE-DEPENDENCE OF FLUORESCENCE FROM LIQUID BUTANE, PENTANE, AND HEXANE - LIFETIMES AND QUANTUM YIELDS

The rate constants for the decay of ultraviolet fluorescence from liquid butane, pentane, and hexane have been measured as a function of temperature between their respective freezing points and near-room temperature. The rate constants are well characterized as the sum of an activated and nonactivated term, as has been described previously. The parameters determining the rate constants are evaluated. Relative fluorescence quantum yields are also measured over the same temperature range. Normalization of the relative fluorescence quantum yields with absolute quantum yields measured previously at 195 K renders the relative determinations absolute. A comparison of the fluorescence results with the photochemical yields shows that a fraction of the initially formed upper excited states dissociates mainly into radicals, in competition with internal conversion to the fluorescing state. © 1990 American Institute of Physics.