The thermal lens effect on laser heating of a metal nano-sphere particle immersed in oil. (September 2020)

• Record Type: Journal Article
• Authors: Gurwich, I.; Spector, M.
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 252(2020)
• Publication Date: 2020-09
• Subjects: Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2020.107066
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: Development of the physical model of beam propagation in thermo-optically nonlinear and non-homogeneous medium. Thermal lensing effect as an origin of saturation and reverse saturation of scattering cross-section of a metal nano-particle. Theoretical validation of intensity dependence of scattering cross-section the heated nano-particle and comparison with the experimental one. Comparison with Mie calculation. Abstract: In this work, we revise the model describing laser heating of a spherical metallic nanoparticle (NP) immersed in transparent oil. We study the generated temperature non-uniformity of the ambient medium and its effect on the propagation of the laser beam. Thus, the model describes the influence of thermal non-uniformity on scattering and absorption of light by the heated particle. Recently, different aspects of the heating of NPs by a laser beam have been actively researched. Some experimental works demonstrated an enigmatic dependence of the effective scattering cross-section of the heated particle on the intensity of the laser beam, illuminating it. The authors of these works labeled the observed effects as "saturation, " and "reverse saturation." In this paper, we show that the propagation of the incident laser beam in a non-uniform oil can by itself be the source of both "saturation" and "reverse saturation" els effects.