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Laser-induced fluorescence (LIF) imaging of mixing processes frequently employs 3-pentanone or toluene as a fluorescence tracer. The analysis of measured LIF signals typically requires corrections for the influence of temperature, pressure, and gas composition on the signal strength in cases where these variables are not constant for the process under study, e.g., in internal combustion engines. However, fluorescence quantum yield data at simultaneous high temperature and high pressure are not well characterized. Therefore, the ability of two fluorescence models to predict the signal strength for 3-pentanone and toluene, respectively, under those conditions has been evaluated through comparison to LIF measurements using 248nm excitation in a motored optical engine. The temperature-pressure manifold that was covered ranges from 0.45bar, 328K to 8bar, 600K. A semi-empirical, photophysical model for 3 …