Question

1. Explain why the energy of photoelectrons in XPS depends on energy of x-ray source, while energy of Auger electrons does not.

Answer 1

Only part of the incident energy from an X-ray source may be used by the ejected electron (some of the energy can be used by the exiting photo electron and some of the energy by the exiting photon).

Auger electrons depend on the energy difference between energy levels of an atom and are fixed - so the ejected electron will have a fixed energy depending on the difference of energy levels of the atom. The Auger effect is called a "radiationless" transition because no radiation is detected outside of the atom.