Size Measurement of Carbon and Iron Nanoparticles by Laser Induced Incadescence

Application of the laser-induced incandescence method for instant size measurements of nanoparticles is considered. Laser heating and subsequent cooling processes of carbon and iron nanoparticles suspended in a gas medium are simulated. The process of laser energy absorption by nanoparticles in Releigh limit is thoroughly analyzed, taking into account time and spatial energy distribution in the laser beam, as well as the cooling of nanoparticles, by collisions with ambient gas molecules of in the free-molecular regime and in the course of evaporation. On the basis of this model, software has been created for analyzing and interpreting the heat radiation signals of laser-heated nanoparticles (laser-induced incandescence) obtained in experiments, as well as for determining their sizes. Using the developed approach, data on the sizes of carbon nanoparticles formed in the course of $\mathrm{C}_2$$\mathrm{H}_2$ pyrolysis, as well as the time profiles of iron nanoparticles produced in the course of laser photolysis of $\mathrm{Fe(CO)}_5$, are obtained and are in good agreement with transmission electron microscopy data.