Page 63 - Academic Press Encyclopedia of Physical Science and Technology 3rd Analytical Chemistry

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Encyclopedia of Physical Science and Technology en001f-44 May 26, 2001 14:57

Auger Electron Spectroscopy

C. L. Briant
Division of Engineering, Brown University, Providence, RI

I. Introduction
II. The Auger Process and Auger
Electron Spectroscopy
III. Applications in Materials Science
IV. Conclusions

GLOSSARY trons to determine the chemical composition of a solid
surface. Because the electrons that are detected are of very
Auger transition Electronic transition that produces low energy, this spectroscopy probes only the top two to
Auger electrons. It occurs in the following way: and five atom layers of the surface. This type of spectroscopy
electron beam impinges on the surface of a solid and is now routinely used in materials research to obtain in-
knocks out a core electron; an outer shell electron de- formation about the composition of solid surfaces.
cays into the hole and in so doing emits energy; this
energy can then knock another electron, the Auger elec-
tron, out of its orbital, and it can escape from the solid I. INTRODUCTION
into the vacuum if the atom is located near the surface.
Grain boundaries Internal interfaces in solids where two Of all the techniques that have been developed to analyze
single crystal grains meet one another. In most solids, surfaces, Auger electron spectroscopy has had the most
the atomic matching between the interfaces is poor. widespread application. In the field of materials science,
Intermetalliccompound Acompoundmadeupoftwoor it has joined such analytical methods as X-ray diffrac-
more metals. The atoms of each metal occupy specific tion and transmission electron microscopy as a staple of
sites on the crystal lattice. The compound is thus said any well-equipped laboratory. It is used in chemistry and
to be ordered. materials science to study the composition of solid sur-
Segregation The process by which the composition of faces and the chemical states of atoms and molecules
on those surfaces. Chemists and physicists study the ba-
a surface or internal interface becomes enriched in a
sic Auger transition to help learn about electronic pro-
particular atomic species. The element reaches the in-
cesses in solids. Those interested in developing electronic
terface by diffusion through the bulk.
equipment have been concerned with providing spec-
trometers with ever-decreasing incident beam diameters
AUGER ELECTRON SPECTROSCOPY is an elec- that will allow the chemical analysis of a surface on a
tron spectroscopy that employs Auger, or secondary, elec- microscopic scale. It is hoped that this article plus the

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