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Investigating laser-nanoparticle interactions using time-resolved laser-induced incandescence

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Robinson-Enebeli_Stephen.pdf (6.19 MB)

Date

2021-01-13

Authors

Robinson-Enebeli, Stephen

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University of Waterloo

Abstract

Nanotechnology is extending the frontiers of science and technology, mainly through the applications of engineered nanomaterials. For instance, metal nanoparticles have seen wide-spread applications in the fields of biomedicine, electronics, manufacturing and fabrication, and environmental remediation. Since the functionalities of nanoparticles are strongly size-dependent, there is a need for an accurate and streamlined diagnostic that meets the growing demand for engineered nanomaterials. Time-resolved laser-induced incandescence (TiRe-LII) is an in situ optical diagnostic technique that characterizes nanoparticle properties in the gas phase. In this technique, nanoparticles suspended in a gas are heated to incandescent temperatures with a laser and allowed to thermally equilibrate with the surrounding gas. The emitted incandescence are size-dependent and provide other information about the physical characteristics of the gas-phase nanoparticles. However, some anomalies have been reported in the literature, including excessive absorption and non-incandescent laser-induced emissions (LIE) that corrupt the TiRe-LII technique and introduce uncertainties to inferred results. In this work, some of the anomalies that originate from the laser-nanoparticle interactions are investigated using the TiRe-LII modelling framework by applying tools such as the fluence study, examining the trends in inferred quantities-of-interest (QoI) that are inferred from an improved spectroscopic and heat transfer submodel, and analyzing LII data from plasmonic nanoparticles. The results show that LIE affects the inference of QoI, and further analysis of LII data from plasmonic nanoparticles can shed light on laser-nanoparticle interactions during TiRe-LII.

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Keywords

nanoparticles, aerosols, optical characterization, LII, heat transfer, laser interaction, Detector calibration, synthesis

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http://hdl.handle.net/10012/16650

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Mechanical and Mechatronics Engineering