LAUSR

Localized surface plasmon (LSP) excitations in metallic nanoparticles (NPs) have recently received increasing attention because of their potential applications in solar energy harvesting, photocatalysis, sensing and biology. Both the LSP resonance energy and peak linewidth depend on the size, shape and environment of the metallic NP, especially for NPs with sizes < 5 nm [1-2]. With smaller metal NPs quantum size effects, surface diffuse scattering and metal-support interactions can all affect their LSP resonant energies and linewidths. The improved energy resolution of the electron energy loss spectroscopy (EELS) in a monochromated STEM (STEM-EELS) makes it possible to study the intrinsic properties of LSPs in individual small metallic NPs [3]. We report here the STEM-EELS investigation of the dependence of LSP linewidths on the Au NPs in the size range of 4-20 nm in diameter.