Nonlinear inelastic electron scattering from Au nanostructures induced by localized surface plasmon resonance

Nonlinear electron scattering is a recently-discovered physical process observed during the localized plasmonic excitation of Ag nanostructures on graphite surface. In the present work, nonlinear electron scattering phenomena is experimentally verified on Au nanostructures by measuring inelastic scattering of electrons field-emitted from tungsten tip. The relative intensity of the electron-energy-loss peak associated with the plasmonic excitation of Au shows again to increase nonlinearly with the electric field generated by the tip-sample bias, demonstrating the generality of nonlinear electron scattering process in plasmonic system. Compared to the nonlinear electron scattering phenomena observed on Ag nanostructures, the nonlinear term for Au nanostructures is about 1 to 2 orders of magnitude smaller, which is in consistent with the field enhancement factor of Au and Ag nanostructures from both the surface-enhanced Raman spectroscopy experiments and the theoretical calculations.