Geometric Effect of High-Resolution Electron Energy Loss Spectroscopy on the Identification of Plasmons: An Example of Graphene

TL;DR

High-resolution electron energy loss spectroscopy (HREELS) can be significantly affected by scattering geometry, which may lead to misinterpretation of plasmon features in graphene, emphasizing the need for quantitative evaluation of geometric effects.

Contribution

This study reveals how scattering geometry influences HREELS measurements and demonstrates the importance of accounting for geometric effects in plasmon identification.

Findings

Scattering geometry impacts HREELS intensity distribution.

Energy loss peaks can be misinterpreted as acoustic plasmons.

Quantitative evaluation of geometric effects is necessary for accurate analysis.

Abstract

High-resolution electron energy loss spectroscopy (HREELS) is one of the most powerful methods to detect the dispersion of plasmons. However, we find that in the HREELS measurement, the scattering geometric configuration will seriously affect the identification of plasmons. Here, taking graphene as an example, using the HREELS capable of two-dimensional energy-momentum mapping combined with the intensity distribution calculations, we visually display the intensity distribution of the scattering geometric factor. We demonstrate that the energy loss peaks from the scattering geometric effect may be misinterpreted as the features of an acoustic plasmon. In any HREELS measurement, it is necessary to evaluate the effect of the scattering geometry quantitatively to identify the intrinsic surface excitations.