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