XPS peak-fitting reference

Select an element for handbook binding energies, expected chemical-state shifts, spin–orbit splitting, branching ratios, and recommended constraints when fitting XPS spectra. 94 elements in the database.

s-blockp-blockd-blockf-blockselectedColored cells with bold symbols have reference data.

Actinium (Ac) — Z=89

Reference binding energies, spin–orbit parameters, and recommended constraints for XPS peak fitting.

Ac 4f7/2

doublet

handbook BE 272.0 eV

Primary BE

272.0 eV

Orbit split (Δ)

7.80 eV

Peak area ratio

4 : 3 (partner : primary)

Typical σ / RSF

0.80 eV · RSF 7.6

Partner line: Ac 4f5/2 at ≈ 279.8 eV (4f7/2 + 7.80 eV).

Peak-fitting constraints

Primary center: Start near 272.0 eV for the elemental / handbook line; refine within chemical-state windows below.
Spin–orbit splitting: Fix 4f5/2 at Ac 4f7/2 + 7.80 eV (≈ 279.8 eV). Keep splitting fixed unless literature justifies otherwise.
Branching / area ratio: Fix partner : primary area ≈ 4 : 3 (branching ratio 0.75). Share FWHM and Lorentzian fraction between doublet components.
Typical width (σ): Initial half-width ≈ 0.80 eV; allow modest variation, prefer shared width across related chemical states of the same orbital.
Relative sensitivity (RSF): Handbook RSF ≈ 7.6 (relative to F 1s = 1.0). Use for quantification, not for constraining peak shape.
Background: Use Shirley (or Tougaard) under the fit window; fit peaks on background-subtracted intensity.

Core-level reference: Moulder1995

Citations used

[Moulder1995] J.F. Moulder, W.F. Stickle, P.E. Sobol, K.D. Bomben, Handbook of X-ray Photoelectron Spectroscopy, Physical Electronics, Eden Prairie, MN, 1995.

Binding energies and chemical-state assignments are compiled from publicly available handbooks and primary literature. Contact Anibal Boscoboinik to report errors or missing attributions.