Landolt-Börnstein - Group III Condensed Matter

6.2.1.2 The EELS experiment

Abstract

This chapter provides an introduction the discussionm on inelastic scattering of electrons. In high resolution electron energy loss spectroscopy (HR-EELS or EELS) electrons with well defined impact energy and direction of incidence impinge on a crystal. The energy spectrum and often the angular distribution of the scattered electrons are measured and related to the frequency and to the momentum of the excited modes. The technique was applied for the investigation of bulk properties using high energy electrons in transmission through thin foils. Primary energies of less than 1 keV are particularly advantageous for surface studies as the mean free path of the electrons has in most materials a minimum of about 1 nm at 100 eV and increases slowly below and above this energy. When electrons in this energy range are backscattered from a solid the interaction is therefore limited to the outermost atomic layers of the crystal. The acronym EELS is used also for studies of interband transitions without analysis of the momentum transfer in which the inelastic signal is collected over a large portion of the solid angle, i.e. integrating over the momentum transfer. A pictorial view of impact and dipole scattering intensity for low energy electron, and an outlook of the kinematics of the electron scattering experiment are figured out. Energy and momentum conservation illustrated by the Ewald construction for in-plane scattering are also shown.

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Title
6.2.1.2 The EELS experiment
Book Title
Interaction of Charged Particles and Atoms with Surfaces
In
6.2.1 Introduction
Book DOI
10.1007/b87125
Chapter DOI
10.1007/10086066_28
Part of
Landolt-Börnstein - Group III Condensed Matter
Volume
24C
Editors
  • G. Chiarotti
  • Authors
  • M. Rocca
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