Effects of LSPR of Gold Nanospheres by Surface Vacancies and Protruding Tips

Abstract

Effects on the optical properties of gold nanospheres are investigated by using discrete dipole approximation (DDA) with respect to variations of surface morphology resulting from introducing protruding tips and vacancy defects. Varied numbers and sizes of tips are attached perpendicular to faces of regular hexahedron and tetrahedron. Surface vacancy defects follow two types; the one with a rotationally carved system and the other with random exclusions of unit systems of DDA. The size of the nanosphere is varied from 10 to 50 nm in radius, and direct comparisons of its effects with modified surfaces have been done. The alteration of optical spectra is investigated with the following properties; extinction, absorption, or scattering cross sections with respect to wavelengths of the incident light in water environment and induced electric field. This work shows that, even with small degree of surface modification, whether it is vacancy or tip, their effects should be taken into consideration, especially for the application to single particle spectroscopy for the aim of extreme sensitivity.