Nanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles

TitleNanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles
Publication TypeJournal Article
Year of Publication2016
AuthorsBertoni, G, Fabbri, F, Villani, M, Lazzarini, L, Turner, S, Van Tendeloo, G, Calestani, D, Gradecak, S, Zappettini, A, Salviati, G
JournalScientific Reports
Volume6
Pagination19168
Date Published2016/01/12/
ISBN Number2045-2322
Keywordsband-gap emission, Cathodoluminescence, energy-loss spectroscopy, enhancement, gold nanoparticles, nanorods, nanostructures, photochemical-synthesis, rapid synthesis, silver nanoparticles
Abstract

Metallic nanoparticles can be used to enhance optical absorption or emission in semiconductors, thanks to a strong interaction of collective excitations of free charges (plasmons) with electromagnetic fields. Herein we present direct imaging at the nanoscale of plasmon-exciton coupling in Au/ZnO nanostructures by combining scanning transmission electron energy loss and cathodoluminescence spectroscopy and mapping. The Au nanoparticles (similar to 30 nm in diameter) are grown in-situ on ZnO nanotetrapods by means of a photochemical process without the need of binding agents or capping molecules, resulting in clean interfaces. Interestingly, the Au plasmon resonance is localized at the Au/vacuum interface, rather than presenting an isotropic distribution around the nanoparticle. On the contrary, a localization of the ZnO signal has been observed inside the Au nanoparticle, as also confirmed by numerical simulations.

Short TitleSci Rep