Investigation of Geometry and Positioning Influence on Optical and Thermal Properties of Gold Nanoparticles.
In COMSOL Multiphysics® RF Module we investigate optical properties of various shapes of gold nanoparticles suspended in water and deposited on a glass substrate. Further, using the Microwave Heating Multiphysics coupling we want to evaluate heating effects related to electromagnetic losses in the system.
The 3D models of studied gold nanostructures (spheres, rods, bipyramids, cubes, cages, prisms) are based on the TEM images of nanoparticles obtained by wet-chemistry synthesis. We study different possible orientations of these objects in respect to each other when in larger sets. Optical constants of gold were taken from [1]. For different linear polarization angles and for left- and right-handed polarized incident light we evaluate linear optical cross-sections (absorption, scattering) as well as plasmonic local field enhancement.
We observe coupling of the nanoparticles’ local fields and thus changes in extinction spectrum. For chiral structures, we note differences in cross-sections for left- and right-handed polarized light which we further evaluate as asymmetry g-factor. For thermal effects, we still expect to obtain single nanoparticles temperature rise as was strictly lead out from diffusion equations for spheres by [2].
We want our simulations to be good support for our work in temperature control in systems containing plasmonic nanoparticles.
References
[1] P. B. Johnson and R. W. Christy, “Optical Constants of the Noble Metals”, Phys. Rev. B 6 (1972), 4370,
[2] Guillaume Baffou and Hervé Rigneault, “Femtosecond-pulsed optical heating of gold nanoparticles” Phys. Rev. B 84 (2011), 035415
