Main Research Publications Members Group Documents Sponsors Afilliations Contact Us |
Plasmon Coupling in 1-D Assemblies of NanostructuresBuilding new plasmonic devices from the bottom up using nanoparticles as elementary building blocks requires a detailed understanding of how properties of the individual nanoparticles change as they are assembled into higher order structures. Energy exchange due to plasmon coupling between nanoparticles depends strongly on the relative distance of the nanoparticles. Additional complexity is introduced when nanoparticles are prepared and assembled by chemical synthesis and soft lithography methods because irregularities or ‘defects’ in particle size, shape, and ordering are inherently present in those systems. However, chemical preparation strategies have the advantage of producing highly crystalline nanoparticles with interparticle separations that are only limited by the thickness of the organic capping material. In order to elucidate the role of imperfections in functional nanomaterials consisting of many particles, it is therefore necessary to correlate structure with the collective optical response on nano to micrometer length scales and compare it to individual nanoparticles.
Our goal is to understand plasmon coupling between metallic nanoparticles in one-dimensional assemblies produced by chemical methods in the
presence of structural irregularities. To address these issues, we are using single particle spectroscopy techniques (absorption and
scattering) that can be correlated with scanning and transmission electron microscopy (TEM and SEM) to determine the optical
properties for specific nanoparticle arrangements. By combining complementary spectroscopy techniques that probe both radiative and
nonradiative plasmonic properties together with structural characterization tools and theoretical modeling, we hope to obtain microscopic insight into how defects
in nanoparticle chains influence the collective plasmon modes.
The figure above shows polarization dependent dark-field scattering images of a ring of 40 nm gold nanoparticles for different detected polarizations as indicated by the arrows (top). SEM of the same nanoparticle ring (bottom left) allows for correlated structural and optical characterization. The dark-field scattering spectra (bottom right) reveal coupled plasmon modes that are polarized parallel to the ring circumference and red-shifted with respect to the 40 nm nanoparticles making up the ring. The assembly of the gold nanoparticles into ring superstructures was developed by our collaborators in the Zubarev Lab. Publications:
|
