Theory of dielectric screening and electron energy loss spectroscopy at surfaces

We present an overview of theoretical techniques for describing electron energy loss processes in a reflection geometry. We start from a fundamental representation of the dielectric susceptibility tensor of the semi-infinite crystal, and illustrate how the screening becomes modified by the presence of the surface. A new formalism is also presented which improves upon existing techniques for modeling energy loss, is fully q-dependent, and accounts for nonlocality. The impact of nonlocality, local field effects and other many-body effects is discussed. The theory is supported by some explicit calculations on the GaAs(001)-c(4 x 4) surface. To cite this article: C Hogan et al., C R. Physique 10 (2009). (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved