ENERGY DISSIPATION AND TRANSITION RADIATION PRODUCED BY THE INTERACTION OF CHARGED PARTICLES WITH A GRAPHENE SHEET

J. L. GERVASONI; S. SEGUI; N. R. ARISTA; Z. L. MISKOVIC

Grenoble

Conferencia; ECOSS 32 - European Conference on Surface Science; 2016

Societé Fracaise du Vide

As a fundamental technique to study the electronic and optical properties ofnanostructures, electron energy loss spectroscopy (EELS) has been extensively used tocharacterize single- and multi-layer graphene. This technique is performed in transmissionelectron microscopes (TEM) with high energy electron beams (around 100 keV), for whichrelativistic effects could be important. Although non-retarded calculations have reproducedexperimental spectra quite succesfully, some aspects of the radiation processes induced bythe incident particle remain unclear, such as the transition radiation patterns in the presenceof plasmon fields. Also, in order to evaluate its importance in TEM experiments, aquantitative assessment of the relativistic correction to the energy loss spectra is necessary.This work addresses these issues by using a relativistic formulation of theelectromagnetic fields, and modeling the conductivity with the well-known dielectricresponse with adequate parameters to describe the electronic properties of graphene.We start with a thorough description of the theory used. In particular, we present detailedexpressions for the electromagnetic fields, the energy loss formulas used to calculate thespectra, and the models of conductivity applied in different regimes. We show and discussthe principal results obtained for doped and neutral graphene monolayers.