Fluorescence lifetime of gas-phase toluene at elevated temperatures

The fluorescence lifetime of toluene in the gas phase upon excitation at 248 nm was investigated as a function of temperature (296–625 K) via time-correlated single-photon counting (TCSPC) in nitrogen bath gas at 1 bar total pressure. The fluorescence decay can be represented by a bi-exponential function. Lifetimes are decreasing with increasing temperature, with the long lifetime component ranging from 45 to 2 ns and the short component from 2 to 0.4 ns in the investigated temperature range. Our results suggest high repetition-rate laser excitation of tracers like toluene in combination with TCSPC as a novel tracer-concentration-independent method for determining gas-phase temperatures.