Laser-induced incandescence on metal nanoparticles: validity of the Rayleigh approximation

摘要： Time-resolved laser-induced incandescence (TiRe-LII) is increasingly being used to characterize non-carbonaceous nanoparticles. However, there exist several measured phenomena, particularly on metal nanoparticles, that cannot be explained using traditional models. This paper shows that some of these phenomena may be due to errors caused by the Rayleigh approximation of Mie theory, which is a standard approach for modeling the spectral absorption of carbonaceous nanoparticles but is generally invalid for metal nanoparticles. Other measurement phenomena can be explained by combining Mie theory with a polydisperse particle size distribution or by considering the change in the refractive index as the nanoparticles melt. Also, the effect of the nanoparticle charge on optical properties is investigated and is found to have a negligible effect on the TiRe-LII model.