Electron energy loss spectroscopy of two-dimensional materials in a scanning electron microscope

This work demonstrates electron energy loss spectroscopy of 2D materials in the 1--20 keV incident electron energy range, observing 50 times stronger electron-matter scattering 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 could greatly benefit from use of this energy regime.