Auger electron spectroscopy (AES) is an analytical technique used to determine the composition of surface layers of a sample. It involves three steps: (1) removing a core electron from an atom via ionization, typically using a 2-10 keV electron beam; (2) an electron dropping to fill the vacancy, releasing energy; (3) this energy causes the emission of an Auger electron. AES collects these low-energy (20-2000 eV) Auger electrons that escape from within 50 angstroms of the surface, allowing it to provide compositional information about just the sample's surface.

1. Auger Electron
Spectroscopy
By:
NanoWhite Group

2. What is AES?
 AES is an analytical techniques for
determining the composition of the
surface layers of a sample.
 Auger spectroscopy can be considered
as involving three basic steps :
 (1) Atomic ionization (by removal of a
core electron)
 (2) Electron emission (the Auger process)
 (3) Analysis of the emitted Auger
electrons

3. 1) Excitation of the atom
causing emission of an
electron
2) An electron drops down to fill
the vacancy created in step 1
3) The energy released in step 2
causes the emission of an Auger
electron.

5. i-ionization
 The Auger process is initiated by creation of a core hole - this is
typically carried out by exposing the sample to a beam of
high energy electrons (typically having a primary energy in
the range 2 - 10 keV). Such electrons have sufficient energy to
ionise all levels of the lighter elements, and higher core levels
of the heavier elements.

6. ii- Electron
Emission
 The ionized atom that remains after the removal of
the core hole electron is, of course, in a highly
excited state and will rapidly relax back to a lower
energy state by one of two routes :
 X-ray fluorescence
 Auger emission

7. iii- Emitted Auger
Electron
 The energy of Auger electrons is usually
between 20 and 2000 eV.
 The depths from which Auger electrons
are able to escape from the sample
without losing too much energy are low,
usually less than 50 angstroms.
 Thus, Auger electrons collected by the
AES come from the surface or just
beneath the surface.
 AES can only provide compositional
information about the surface of the
sample.

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