10.1021/acs.jpcc.9b06592.s001
Rachel E. Armstrong
Rachel E.
Armstrong
J. C. van Liempt
J. C.
van Liempt
Peter Zijlstra
Peter
Zijlstra
Effect of Film Thickness on the Far- and Near-Field
Optical Response of Nanoparticle-on-Film Systems
American Chemical Society
2019
enhancement
quadrupole
surface-enhanced Raman spectroscopy
antenna mode
antenna mode wavelength
study field-mediated processes
Near-Field Optical Response
film thickness
near-field
2019-10-10 13:38:05
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Effect_of_Film_Thickness_on_the_Far-_and_Near-Field_Optical_Response_of_Nanoparticle-on-Film_Systems/9963704
We study the near-field
and far-field optical responses of nanoparticle-on-film
systems using single-nanoparticle spectroscopy and numerical simulations.
We find that the optical spectra contain three dominant modes: a transverse
dipole, quadrupole mode, and a dominant vertical antenna mode. We
vary the thickness of the metal film from 10 to 45 nm and find that
the vertical antenna mode wavelength is nearly independent of the
film thickness. In contrast, we find that the associated near-field
enhancement in the gap between the particle and the film strongly
depends on the film thickness. This trend is also observed in the
far field where the vertical antenna mode strongly increases in amplitude
relative to the quadrupole for the increasing film thicknesses up
to the skin depth of gold. These findings are in good agreement with
a numerical model and pave the way to study field-mediated processes
such as fluorescence, surface-enhanced Raman spectroscopy, and localized
chemistry at the same resonance wavelength but at varying degrees
of field enhancement.