Local Electron Beam Excitation and Substrate Effect on the Plasmonic Response of Single Gold Nanostars

TL;DR

This study uses high-resolution cathodoluminescence spectroscopy combined with numerical simulations to analyze how local electron beam excitation and substrate influence the plasmonic responses of individual gold nanostars.

Contribution

It introduces a combined experimental and simulation approach to map and understand the localized plasmon modes of gold nanostars on substrates.

Findings

Different plasmon modes are spatially and spectrally resolved.

Substrate effects significantly alter the plasmonic response.

High spatial resolution mapping reveals detailed mode structures.

Abstract

We performed Cathodoluminescence (CL) spectroscopy and imaging in a high resolution scanning electron microscope to locally and selectively excite and investigate the plasmonic property of a multibranched gold nanostar on silicon substrate. This method allows us to map the local density of optical states from the nanostar with a spatial resolution down to a few nanometers. We resolve both in spatial and spectral domain, different plasmon modes associated with the nanostar. Finite- difference time-domain (FDTD) numerical simulations are performed to support the experimental observations. We investigate the effect of substrate on the plasmonic property of these complex shaped nanostars. The powerful CL-FDTD combination helps us to understand the effect of the substrate on plasmonic response of branched nanoparticles.