Titanium

Doublet Separations

Doublet Separations – Titanium exhibits different doublet separations based on oxidation state.

Ti 2p (metal): 6.1 eV
Ti 2p (nitride): 6.0 eV
Ti 2p (oxide): 5.7 eV

Available Photoemissions and Energies

The Energies Listed are Binding Energies!

Ti 2s: 566 eV
Ti 2p: 454 eV
Ti 3s: 59 eV
Ti 3p: 34 eV

Common Element Overlaps

The Energies Listed are Binding Energies!

Ti is primarily analyzed via the 1s orbital

Er 4s (449 eV)
In 3d (451 eV)
Ru 3p (461 eV)
Ru 3p (461 eV)
Bi 4d (464 eV)
Ta 4p (465 eV)

Augers and Energies

Energies listed are Kinetic Energies!

Ti LMM: ~ 410 eV

Common Species Binding Energies

The Energies Listed are Binding Energies!

Species	E_B / eV	Doublet Separation / eV	Charge Ref	Ref
Ti metal	454	6.1	Au 4f (84 eV)	3
TiN	455.3	6	Au 4f (84 eV)	3
TiO₂	459.3	5.7	Au 4f (84 eV)	4
Ti₂O₃ (Ti³⁺)	456.6		C 1s (284.6 eV)	5
TiO (Ti²⁺)	454.4		C 1s (284.6 eV)	5
TiS₂	456		C 1s (284.6 eV)	5
TiS₃	455.9		C 1s (284.6 eV)	5

Table 1: Typical binding energies for various common Ti species

Background and Theory

Calculations confirm there is some multiplet structure associated with Ti(II) and Ti(III) free ions, though this may not be well resolved in XPS spectra.

The sources do not specifically discuss shake-up satellites in titanium spectra, but it is mentioned that shake-up structure can complicate the interpretation of transition metal 2p spectra.(6)

Experimental Advice

TiO₂ is readily reduced by Ar⁺ sputtering, forming suboxides.

XPS of titanium is typically performed on the 2p region. Unlike later first row TMs Ti 2p does not undergo multiplet splittings in it’s compounds, due to a lack of unpaired d-electrons. Ti 2p does, however, feature asymmetric peak broadening due to a Coster-Kronig transition and so care should be taken when peak fitting. The Ti 2p_1/2 may be fit with a FWHM wider than that of the Ti 2p_3/2.

Ti 2p peaks are mostly uncomplicated doublets (Figure 1) with a separation of around 6 eV (see table 1).

Figure 1: TiO₂ Ti 2p XPS⁽¹⁾

The exception to this is titanium nitride (TiN) which exhibits a complex structure including shake-up peaks, bulk and surface plasmons.⁽²⁾

Kumar, S., et al. (2017). “P25@ CoAl layered double hydroxide heterojunction nanocomposites for CO2 photocatalytic reduction.” Applied Catalysis B: Environmental 209: 394-404. Read it online here.
Jaeger, D. and J. Patscheider (2013). “Single crystalline oxygen-free titanium nitride by XPS.” Surface Science Spectra 20(1): 1-8. Read it online here.
Badrinarayanan, S., et al. (1989). “XPS studies of nitrogen ion implanted zirconium and titanium.” Journal of Electron Spectroscopy and Related Phenomena 49(3): 303-309. Read it online here.
Diebold, U. and T. Madey (1996). “TiO2 by XPS.” Surface Science Spectra 4(3): 227-231. Read it online here.
Gonbeau, D., et al. (1991). “XPS study of thin films of titanium oxysulfides.” Surface science 254(1-3): 81-89. Read it online here.
Biesinger, Mark C., et al. “Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn.” Applied surface science 257.3 (2010): 887-898. Read it online here.