Sizing of Non-Carbonaceous Nanoparticles by Time-Resolved Laser-Induced Incandescence

Abstract

Non-carbonaceous nanoparticles represent a growing field in science and technology. Their applications range from medicine to environmental remediation to information technology. As the functionality of nanoparticles in these roles is highly size dependent, it is critical that diagnostics be developed to accurately measure the size of these nanoparticles. Time-resolved laser-induced incandescence (TiRe-LII) is an in situ technique that can measure the size of nanoparticles without physically probing a system. The technique operates using a laser pulse that heats the nanoparticle to incandescent temperatures. The incandescence is then measured from the nanoparticles as they equilibrate with the surrounding gas. As smaller particles will cool more quickly, the size of the nanoparticles can be inferred by modeling the incandescence or, more commonly, the effective temperature decay of the nanoparticles. The present work summarizes attempts to extend the use of TiRe-LII from its original application on soot to non-carbonaceous particles. This will be done by examining experimental data from three non-carbonaceous nanoparticles: molybdenum, silicon, and iron. This includes descriptions of the TiRe-LII models and statistical techniques required to robustly infer parameters and their uncertainties. As one of the major setbacks in extending this technique to other materials is the determination of the thermal accommodation coefficient (TAC), this work also focusses on determining that parameter both from experimental data and molecular dynamics simulations.