title: SERS of Individual Nanoparticles on a Mirror: Size Does Matter, but so Does Shape.
abstract: Coupling noble metal nanoparticles by a 1 nm gap to an underlying gold mirror confines light to extremely small volumes, useful for sensing on the nanoscale. Individually measuring 10 000 of such gold nanoparticles of increasing size dramatically shows the different scaling of their optical scattering (far-field) and surface-enhanced Raman emission (SERS, near-field). Linear red-shifts of the coupled plasmon modes are seen with increasing size, matching theory. The total SERS from the few hundred molecules under each nanoparticle dramatically increases with increasing size. This scaling shows that maximum SERS emission is always produced from the largest nanoparticles, irrespective of tuning to any plasmonic resonances. Changes of particle facet with nanoparticle size result in vastly weaker scaling of the near-field SERS, without much modifying the far-field, and allows simple approaches for optimizing practical sensing.
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Avenue, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Felix
authors.initials: F
authors.lastname: Benz
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Avenue, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Rohit
authors.initials: R
authors.lastname: Chikkaraddy
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Avenue, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Salmon
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Avenue, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Hamid
authors.initials: H
authors.lastname: Ohadi
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Avenue, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Bart
authors.initials: B
authors.lastname: de Nijs
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Avenue, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Mertens
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Avenue, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Cloudy
authors.initials: C
authors.lastname: Carnegie
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Avenue, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Bowman
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Avenue, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Baumberg