title: How Light Is Emitted by Plasmonic Metals.
abstract: The mechanism by which light is emitted from plasmonic metals such as gold and silver has been contentious, particularly at photon energies below direct interband transitions. Using nanoscale plasmonic cavities, blue-pumped light emission is found to directly track dark-field scattering on individual nanoconstructs. By exploiting slow atomic-scale restructuring of the nanocavity facets to spectrally tune the dominant gap plasmons, this correlation can be measured from 600 to 900 nm in gold, silver, and mixed constructs ranging from spherical to cube nanoparticles-on-mirror. We show that prompt electronic Raman scattering is responsible and confirm that "photoluminescence", which implies phase and energy relaxation, is not the right description. Our model suggests how to maximize light emission from metals.
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Mertens
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
authors.forename: Marie-Elena
authors.initials: ME
authors.lastname: Kleemann
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
authors.forename: Rohit
authors.initials: R
authors.lastname: Chikkaraddy
authors.affiliation: Faculty of Arts and Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Prineha
authors.initials: P
authors.lastname: Narang
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
authors.forename: Jeremy J
authors.identifier: 0000-0002-9606-9488
authors.initials: JJ
authors.lastname: Baumberg
keywords: Landau damping; Plasmon; nanogap; nanoparticle on mirror; photoluminescence