Energy Resolution


Energy Resolution versus Count-Rate






Natural FWHM of Metals < Natural FWHM of Metal Oxides

FWHM of Pure Element is normally ~2x smaller than the FWHM of the Pure Metal Oxide – This is not related to energy resolution or pass energy settings.

  • Pure Metal FWHM range from 0.3 to ~1.3 eV for the main XPS signal
  • Metal Oxide FWHM range from ~1.0 to ~1.8 eV for the main XPS signal


This is an overlay of the Mg (2p) spectra from pure ion etched Mg metal, and pure MgO single crystal (fresh exposed bulk).
The BE of the MgO spectrum was shifted ~2 eV to align the peak maxima of both signals.




FWHM of Chemical Compounds





FWHM of Pure Metals from XPS using Monochromatic and Non-Monochromatic X-rays