  Tunability of the surface plasmon resonance wavelength is demonstrated by
varying the thickness of Al2O3 spacer layer inserted between the graphene and
nanoparticles. By varying the spacer layer thickness from 0.3 to 1.8 nm, the
resonance wavelength is shifted from 583 to 566 nm. The shift is due to a
change in the electromagnetic field coupling strength between the localized
surface plasmons excited in the gold nanoparticles and a single layer graphene
film. In contrast, when the graphene film is absent from the system, no
noticeable shift in the resonance wavelength is observed upon varying the
spacer thickness.

Materials Science;Mesoscale and Nanoscale Physics