AES Theory: Auger Analytical Volumes

Electron beams disperse into small volumes, typically about one cubic micron (1e-12 cc). X-rays are emitted from most of this volume. Auger signals arise from much smaller volumes, down to about 3e-19 cc.

The X-ray analytical volume increases with electron beam energy and decreases for materials with higher atomic numbers. The Auger analytical volume depends on the beam diameter and on the escape depth of the Auger electrons. The mean free paths of electrons depend on their energies and on the sample material. The minimum mean free path (~0.5 nm) occurs at about 80 eV. Under practical analytical conditions the mean free path increases to as much as ~25 nm.

[Previous Topic] [Next Topic]