The ability to obtain laser based quantitative temperature measurements is particularly important in high pressure environments. In this study, quantitative temperature measurements using Laser Induced Thermal Grating Spectroscopy (LITGS) were employed for a toluene vapor/air jet varying the toluene concentration and pump laser power. In LITGS, the gas temperature at the crossing point of two pump laser beams can be derived from the oscillation frequency of the LITGS signal and, in principle, the signal at high pressure is larger than that at atmospheric pressure. Thus, LITGS is a promising laser diagnostic method for high pressure environments. LITGS signal was acquired for toluene vapor/air mixtures at atmospheric pressure and room temperature and it was found that the derived temperature is influenced by the energy of incident pump laser, showing an increase with an increase in the pump energy. A semi-empirical equation showing the relationship between the relative temperature rise, pump energy and mole fraction was then derived. The experimental results match the linear semi-empirical equation.
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