EXCIPLEX LIQUID-PHASE THERMOMETER USING TIME-RESOLVED LASER-INDUCED FLUORESCENCE

Pulsed photoexcitation of hydrocarbon fuels doped with organic molecul es exhibits a temperature-dependent fluorescence spectrum that is used as the basis for a weakly intrusive optical thermometer. By use of pu lsed excitation from a 308-nm 8-ns XeCl excimer laser with gated detec tion of the fluorescence emissions from doped n-heptane, we demonstrat e that time-resolved measurement of the excited monomer and the redshi fted excited-state complex (exciplex) fluorescence emissions can yield sub-1(.) accuracy for temperatures ranging from 440 K to the vicinity of the critical temperature (540 K). The experiments also show; that the exciplex fluorescence spectrum is pressure independent below and a bove supercritical pressure. (C) 1998 Optical Society of America.