Experimental and theoretical studies of surface plasmon excitation from nanometer size metallic particles using the scanning transmission electron microscope

This thesis contains theoretical and experimental results on the studies of small metallic particles using the Scanning Transmission Electron Microscope (STEM). Surface plasmon excitations have been studied as a probe to the electronic structure of such particles.;In addition, in order to be able to more thoroughly characterize nanometer scale particles in the STEM, a design study was undertaken to determine the feasibility of utilizing a high performance Auger spectrometer coupled to the high resolution condensor-objective lens in the STEM. An aberration corrected system has been simulated which appears to have higher performance than other reported designs at the same electron optical conditions.;A general macroscopic theory has been developed to predict the electron energy loss spectrum due to surface plasmon excitation. This theory has been used to model the experimental system of metallic particles on supporting dielectric substrates. Experiments have been performed to observe the deviation of the surface plasmon excitation energy from the prediction of the macroscopic theory when the particle size becomes small. The excitation energy was found to exhibit a minimum when the particle diameter is about 100 A. It increases for smaller diameters and increases towards the value predicted by macroscopic theory at larger diameters; increase again at smaller diameters. Such change in energy is not predicted by the macroscopic local theory.