High-Temperature, Oxygen-Resistant Molecular Fluorescence Thermometers

Four strongly emitting fluorescent molecules have been identified as effective liquid-phase thermometers for use at temperatures as high as 175 °C under oxygen-saturated conditions. In each case, the thermometry is based on shifts and/or changes in the shape of the fluorescence emission with temperature. The four molecules and the temperature ranges tested were POPOP [1,4-di(2-(5-phenyloxazoyl)benzene], 25–150 °C; NPO [2-(1-naphthyl)-5-phenyloxazole], 25–173 °C; BTBP [ N,N-bis(2,5-di-tert-butylphenyl)-3,4,9,10-perylene dicarboximide], 25–173 °C; and BPB [benzo(ghi)perylene], 25–171 °C. Six other laser dyes were tested and were found to be unsatisfactory.