Focus on Recent advances in (S)TEM and related spectroscopies: a tribute to C. Colliex

Capturing EELS in the reciprocal space

C. Hébert^a1a2 c1, A. Alkauskas^a1a2, S. Löffler^a3, B. Jouffrey^a4 and P. Schattschneider^a4a5

Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, Switzerland

Interdisciplinary Center for Electron Microscopy, École Polytechnique Fédérale Lausanne, Switzerland

Institute of Solid State Physics, Vienna University of Technology, Austria

LMSS-Mat, CNRS-UMR 8579, École Centrale Paris, Châtenay-Malabry, France

University Service Centre for Transmission Electron Microscopy, Vienna University of Technology, Austria

Abstract

In this work two aspects of momentum-dependent electron energy loss spectrometry are studied, both in the core-loss and in the low-loss region. In the case of core losses, we focus on the demonstration and the interpretation of an unexpected non-Lorentzian behavior in the angular part of the double-differential scattering cross-section. The silicon L3 edge is taken as an example. Using calculations we show that the non-Lorentzian behavior is due to a change in the wavefunction overlap between the initial and the final states. In the case of low losses, we first analyze the momentum-dependent loss functions of coinage metals Cu, Ag, and Au. We then demonstrate how advanced electronic structure calculations can be used to build simple models for the dielectric function that can then serve as a basis for the calculation of more complicated sample geometries.

(Received November 22 2010)

(Revised February 16 2011)

(Accepted April 15 2011)

(Online publication June 20 2011)

Correspondence:

^c1 cecile.hebert@epfl.ch