6533b872fe1ef96bd12d3aa8

RESEARCH PRODUCT

Near Field of Strongly Coupled Plasmons: Uncovering Dark Modes

Gerd SchönhenseF. SchertzMarcus SchmelzeisenHans-joachim ElmersReza MohammadiMaximilian Kreiter

subject

PhysicsScatteringMechanical EngineeringPhysics::OpticsBioengineeringNear and far fieldGeneral ChemistryElectronCondensed Matter PhysicsLight scatteringPhotoemission electron microscopyDipoleGeneral Materials ScienceAtomic physicsSpectroscopyPlasmon

description

Strongly coupled plasmons in a system of individual gold nanoparticles placed at subnanometer distance to a gold film (nanoparticle-on-plane, NPOP) are investigated using two complementary single particle spectroscopy techniques. Optical scattering spectroscopy exclusively detects plasmon modes that couple to the far field via their dipole moment (bright modes). By using photoemission electron microscopy (PEEM), we detect in the identical NPOPs near-field modes that do not couple to the scattered far field (dark modes) and are characterized by a strongly enhanced nonlinear electron emission process. To our knowledge, this is the first time that both far- and near-field spectroscopy are carried out for identical individual nanostructures interacting via a subnanometer gap. Strongly resonant electron emission occurs at excitation wavelengths far off-resonant in the scattering spectra.

https://doi.org/10.1021/nl204277y