Vanadium

Vanadium • Transition Metal

Primary XPS region: V2p
Overlapping regions: O1s
Binding energies of common chemical states:

Experimental information

• Collect both the V2p and O1s regions together (507eV–540eV).
  
  • It is important to have the V2p/O1s regions together for accurate peak fitting.

Interpretation of XPS spectra

• When vanadium is present in low concentration (compared to oxygen), look carefully for spin-orbit split peaks to lower binding energy side of O1s peak for identification of vanadium.
• V metal gives asymmetric peaks shapes in the V2p region.
  • Oxides will have symmetric peak shapes.
• V2p peak has significantly split spin-orbit components (Δ_metal=7.6eV).
  • Splitting Δ-value varies with chemical state (e.g., Δ_V2O5=7.4eV).
  • Typically FWHM for each spin-orbit component is the same, but for V2p the V2p_1/2 component is much broader than the V2p_3/2 peak.
    • Consequently, V2p_1/2 peak is much shorter than expected.
• When oxygen is present on the sample surface, the V2p and O1s regions should be fitted together, using a single Shirley or Smart background across both regions.
  • If this procedure is not followed, the relative intensities of the V2p_3/2 and V2p_1/2 will be significantly different to the expected ~2:1 ratio.

References

• [1] MC Biesinger et al., Applied Surface Science 257 (2010) 887-898.