Plasmon excitations in metallic nanostructures

A new hyperspectral imaging technique and apparatus for imaging plasmon excitations and cathodoluminescence in nanostructures with nanoscale resolution have been developed. The apparatus, based on a scanning electron microscope synchronized with a multi-channel spectrum analyzer, allows for collection and detection of optical electron-induced emission from a sample in two configurations (high efficiency and high angular resolution modes) and in the wavelength region from 350 to 1150 nm with 0.8 nm spectral resolution and high quantum efficiency. It was demonstrated that the electromagnetic field structure near a plasmonic nanoparticle forms a vortex. It was shown that the power-flow lines of linear polarized monochromatic light interacting with a metal λ/20 nanoparticle, in the proximity of its plasmon resonance, form whirlpool-like nanoscale optical vortices (optical whirlpools). Both spherical and spheroidal particles were studied using analytical Mie theory and the Finite Element method. One of two types of vortices, inward or outward, was observed depending on the sign of frequency detuning between the external field and plasmon resonance of the nanoparticle.EThOS - Electronic Theses Online ServiceGBUnited Kingdo