The temperature dependence of the shift of the Raman peak has been commonly used to measure the temperature. Surprisingly, the temperature measured using Raman spectrometry during plasmonic heating is much lower than the expected temperature from the melting of the TiO2 NPs. Here, a shift in the ~ 446 cm -1 Raman peak was used to measure the change in temperature during and after irradiation of the P25-Au mixture. Eg mode (~ 446 cm -1 ) in the rutile phase has a significant frequency shift as the temperature changes. The 20 x 20 μm 2 Raman map was simultaneously collected when an on-resonance 532 nm laser at 16 mW power (Figure ) irradiated the P25-Au sample. The laser exposure time at each pixel during the scan was 500- milliseconds. Raman spectra (Figure ) from five different spots (marked in red) obtained during the scan show variation of peak shifts of the Eg mode at 422, 424, 423, 415, and 414 cm -1 . f) The dependence of the temperature of Au nanoparticle on the power of 532 nm laser and 638 nm calculated based on isolated single particle self-heating (black, Tnano) and collective/global heating (red, Tglobal).