Covalency in Fe₂O₃ and FeO: Consequences for XPS satellite intensity

Area of Science:

• Materials Science
• Solid-State Chemistry
• Computational Chemistry

Background:

• Understanding metal-ligand interactions is crucial for characterizing materials.
• Iron oxides exhibit variable oxidation states, influencing their electronic properties.
• X-ray Photoelectron Spectroscopy (XPS) is a key technique for surface analysis and stoichiometry determination.

Purpose of the Study:

• To investigate the covalent character of metal-oxygen bonds in Fe(II)O and Fe(III)2O3.
• To analyze how covalency changes in different oxidation states and ionized configurations.
• To correlate changes in covalency with XPS spectral features like relaxation energies and shake satellites.

Main Methods:

• Theoretical analysis of wave functions.
• Examination of ground and ionic states (Fe 3p and Fe 2p electron removal).
• Computational modeling of electronic structure.

Main Results:

• Covalency differs significantly between Fe(II)O and Fe(III)2O3.
• Ionization leads to considerable changes in covalent character.
• Altered covalency directly impacts relaxation energies and satellite intensities in XPS spectra.

Conclusions:

• The study provides a theoretical basis for interpreting XPS data of iron oxides.
• Changes in covalency are key to understanding XPS spectral variations.
• Findings are applicable to determining the stoichiometry of iron oxides and other 3d transition metal oxides.