1 research outputs found
Near Field of Strongly Coupled Plasmons: Uncovering Dark Modes
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