Controlling subnanometer gaps in plasmonic dimers using graphene.
Graphene is used as the thinnest possible spacer between gold nanoparticles and a gold substrate. This creates a robust, repeatable, and stable subnanometer gap for massive plasmonic field enhancements. White light spectroscopy of single 80 nm gold nanoparticles reveals plasmonic coupling between the particle and its image within the gold substrate. While for a single graphene layer, spectral doublets from coupled dimer modes are observed shifted into the near-infrared, these disappear for increasing numbers of layers. These doublets arise from charger-transfer-sensitive gap plasmons, allowing optical measurement to access out-of-plane conductivity in such layered systems. Gating the graphene can thus directly produce plasmon tuning.
NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
Jan
J
Mertens
Anna L
AL
Eiden
Daniel O
DO
Sigle
Fumin
F
Huang
Antonio
A
Lombardo
Zhipei
Z
Sun
Ravi S
RS
Sundaram
Alan
A
Colli
Christos
C
Tserkezis
Javier
J
Aizpurua
Silvia
S
Milana
Andrea C
AC
Ferrari
Jeremy J
JJ
Baumberg