Reflection Shifts in Gold Nanoparticles

Metal nanoparticles are widely researched for the fabrication of novel lowcost and more energy efficient optoelectronic devices. Optical properties of metalnanoparticles are known to be different from their bulk counterparts. In this paper, withan appropriate modification of Drude model, I provide an improved dielectric functionfor gold nanoparticles which accounts for particle size as well as temperature effects. Themodel is consequently used to investigate Goos-Hanchen and Imbert-Fedorov reflectionshifts of an oblique linearly polarized laser beam reflected from the nanoparticles invarious temperatures. It is shown that the beam light can contribute both spatial andangular shifts depending on its state of polarity. The maximum shifts take place at grazingangles when the polarization of light is set at TM and ۴۵°. Study of the light deviations'sensitivity to the temperature indicates that reflection shifts decrease linearly at highertemperatures except in angular out-of-plane shift Θ𝐼𝐹 . The trend is incremental fordifferent nanoparticle size, keeping the distinct behavior of Θ𝐼𝐹 . Such results allow moreaccurate prediction of many optical phenomena involving nanoscaled gold and may serveas a delicate method to determine nanoparticles' size.