How does Auger electron spectroscopy work?

How does Auger electron spectroscopy work?

In Auger electron spectroscopy (AES), we bombard a sample surface with a focused beam of high-energy (2- to 10-kV) electrons. The incident electrons lose energy to the sample atoms, generating Auger electrons that have discrete kinetic energies characteristic of the emitting atoms.

How are Auger electrons generated?

So-called Auger electrons are emitted when an electron beam hitting the surface creates electron holes in a lower shell (K, L or M) and when this hole is filled by an electron from a higher shell. The excess energy of this jump is transferred to another electron which is emitted.

Who discovered Auger electron Spectroscopy?

Historically, the Auger effect was discovered independently in 1922 by L. Meitner [1], an Austrian physicist, and later in 1923 by Pierre Auger, a French physicist. Figure 11.1.

Why is AES surface sensitive?

Surface sensitivity in AES arises from the fact that emitted electrons usually have energies ranging from 50 eV to 3 keV and at these values, electrons have a short mean free path in a solid.

What is the difference between Auger electron and secondary electron?

Auger Electrons have a characteristic energy, unique to each element from which it was emitted from. Since a lower (usually K-shell) electron was emitted from the atom during the secondary electron process an inner (lower energy) shell now has a vacancy.

What is Auger transition?

The Auger effect is a process by which electrons with characteristic energies are ejected from atoms in response to a downward transition by another electron in the atom. Sometimes this transition will be accompanied by an emitted photon whose quantum energy matches the energy gap between the upper and lower level.

What are Auger electrons?

Auger electrons are electrons that are emitted when an electron from a higher energy level falls into a vacancy in an inner shell.

How the Auger effect is produced?

The Auger effect is a process by which electrons with characteristic energies are ejected from atoms in response to a downward transition by another electron in the atom.

What does an Auger electron energy depend on?

Fig. 8. Schematic of Auger electron emission of from an atom with an inner shell core hole. The kinetic energy (KE) of the emitted Auger electron depends on the specific Auger transition that occurs (ie, KLL) and the chemical environment of the atom.

What is Auger analysis?

Auger Analysis, Auger Electron Spectroscopy (AES or Auger) is a chemical surface analysis method. AES measures the chemical composition of the outermost 100 Å of a sample. Measurements can be made at greater depths by ion sputter etching to remove surface layers.

Are Auger electrons secondary electrons?

Each incident electron can produce several secondary electrons. A higher energy electron from the same atom can “fall” to a lower energy, filling the vacancy. This creates and energy surplus in the atom which can be corrected by emitting an outer (lower energy) electron; an Auger Electron.

How is the specificity of Auger Electron Spectroscopy?

AES employs a beam of electrons as surface a probe. Only those electrons that emerge from the topmost atomic layers contribute to the spectrum so giving rise to the high surface specificity of this technique.