Diffuse Surface Scattering in the Plasmonic Resonances of Ultralow Electron Density Nanospheres.
Localized surface plasmon resonances (LSPRs) have recently been identified in extremely diluted electron systems obtained by doping semiconductor quantum dots. Here, we investigate the role that different surface effects, namely, electronic spill-out and diffuse surface scattering, play in the optical properties of these ultralow electron density nanosystems. Diffuse scattering originates from imperfections or roughness at a microscopic scale on the surface. Using an electromagnetic theory that describes this mechanism in conjunction with a dielectric function including the quantum size effect, we find that the LSPRs show an oscillatory behavior in both position and width for large particles and a strong blue shift in energy and an increased width for smaller radii, consistent with recent experimental results for photodoped ZnO nanocrystals. We thus show that the commonly ignored process of diffuse surface scattering is a more important mechanism affecting the plasmonic properties of ultralow electron density nanoparticles than the spill-out effect.
†Departamento de Fı́sica Teórica de la Materia Condensada C5 and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain.
R Carmina
RC
Monreal
‡Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland.|¶Department of Applied Physics and Gothenburg Physics Centre, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
Tomasz J
TJ
Antosiewicz
¶Department of Applied Physics and Gothenburg Physics Centre, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
S Peter
SP
Apell
diffuse surface scattering; localized surface plasmon resonances; semiconductor quantum dots