Carrier Dynamics in Ultrathin Gold Nanowires: Role of Auger Processes

Abstract

Carrier dynamics in metallic nanostructures is strongly influenced by their confining dimensions. Gold nanoparticles of size $\sim ~2$ nm which fill the transition space separating metallic and non-metallic behavior. In this work, we report carrier dynamics in high aspect ratio ultrathin gold nanowires (Au-UNWs) of average diameter $\sim $ 2 nm using pump (3.1 eV) and coherent white light continuum as probe in the spectral range of 1.15 to 2.75 eV. The transient carrier dynamics in Au-UNWs under extreme excitation regime is slower than predicted by the often used two-temperature model. We identify Auger-assisted carrier heating process which slows down the hot carrier cooling dynamics. The rate equation model fitted to the data yields an estimate of Auger coefficient for gold nanostructures.