Characterization of Laser-Induced Emission of high-purity TiO2 nanoparticles: Feasibility of Laser-Induced Incandescence
Résumé
The development of Laser-Induced Incandescence (LII) approach for characterizing the production of high-purity non-carbonaceous metaloxides produced in flame synthesis systems is in progress. This work aims to prove the feasibility of LII measurement for titanium dioxide (TiO2). In previous works, laser-induced emission (LIE) was investigated for flame-synthetized TiO2 particles. However, the presence of carbon materials was detected. As this calls into question the nature of the signal, we consider in this work LIE of high-purity engineered TiO2 nanoparticles to circumvent the carbon issue. Specifically, we investigate the spectral and temporal laser-induced emissions of pure TiO2 nanoparticles dispersed in a non-reactive environment. In parallel, LIE from carbon black is examined to validate the strategy and to highlight differences between carbon black and TiO2. The TiO2 results indicate that depending on the laser fluence, different interferences appear at prompt. The literature suggests that these non-thermal emissions are likely to be from fluorescence or phase-selective laser-induced breakdown spectroscopy, both characterized by a short lifetime. To avoid these parasitics signals, measurement acquisition time is delayed. A spectral Characterization of Laser-Induced Emission of high-purity TiO 2 nanoparticles red-shift is observed with time as a result of decreasing particle temperature. This proves the LII nature of delayed emission from pure TiO2, which is confirmed by the LII-like nature of the temporal signals.
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