Introduction

Abstract

Nano, a word derived from the Greek word $\nu \alpha \nu o\varsigma$ (nanos, which translated denotes “dwarf”), is nowadays a synonym for a whole research area—the nanosciences. One area within this huge research field is nano-optics, where the response of a nanoparticle to an incoming light wave is investigated. In detail, nanoparticles made of noble metals evoke a special interest, since these particles show a strong response to the incoming light wave. This attribute can be explained by the effect that the mentioned light wave excites the electrons in the conduction band to a collective oscillation. If the frequency of the incoming light matches the eigenfrequency of the electron-oscillation, a resonance occurs, which then leads to strong scattering and absorption of the incoming light. To allow a physical explanation of this phenomena, the collective oscillation of the electrons is described as a quasiparticle, which is termed plasmon.