title: Nanooptics of molecular-shunted plasmonic nanojunctions.
abstract: Gold nanoparticles are separated above a planar gold film by 1.1 nm thick self-assembled molecular monolayers of different conductivities. Incremental replacement of the nonconductive molecules with a chemically equivalent conductive version differing by only one atom produces a strong 50 nm blue-shift of the coupled plasmon. With modeling this gives a conductance of 0.17G(0) per biphenyl-4,4'-dithiol molecule and a total conductance across the plasmonic junction of 30G(0). Our approach provides a reliable tool quantifying the number of molecules in each plasmonic hotspot, here <200.
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, University of Cambridge , JJ Thomson Ave, Cambridge, CB3 0HE, United Kingdom.
authors.forename: Felix
authors.initials: F
authors.lastname: Benz
authors.forename: Christos
authors.initials: C
authors.lastname: Tserkezis
authors.forename: Lars O
authors.initials: LO
authors.lastname: Herrmann
authors.forename: Bart
authors.initials: B
authors.lastname: de Nijs
authors.forename: Alan
authors.initials: A
authors.lastname: Sanders
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Sigle
authors.forename: Laurynas
authors.initials: L
authors.lastname: Pukenas
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Evans
authors.forename: Javier
authors.initials: J
authors.lastname: Aizpurua
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Baumberg
keywords: Sensing; molecular conductivity; nanophotonics; plasmonic coupling; plasmonics; surface-enhanced Raman spectroscopy