Electron Energy Loss Spectroscopy of 2D Materials in a Scanning Electron Microscope

TL;DR

This paper demonstrates electron energy loss spectroscopy of 2D materials using low-energy electrons in a scanning electron microscope, revealing significantly stronger coupling and potential for improved nanostructure analysis.

Contribution

It introduces the use of 1-30 keV electron energies for EELS of 2D materials, showing enhanced coupling and extending the universal scattering curve to this regime.

Findings

100-times stronger electron-matter coupling at 1-30 keV

Universal scattering curve applies with a scale factor

Optimal coupling energy range identified for 2D materials

Abstract

This work demonstrates electron energy loss spectroscopy of 2D materials in a 1-30 keV electron microscope, observing 100-times stronger electron-matter coupling relative to 125 keV microscopes. We observe that the universal curve relating beam energy to scattering holds for the transition from bulk graphite to graphene, albeit with a scale factor. We calculate that optimal coupling for most 2D materials and optical nanostructures falls in this range, concluding that spectroscopy of such systems will greatly benefit from use of this previously unexplored energy regime.