Knowledge Base

Doublet Separations

• La 3d: 16.8 eV
• La 4d: 2.85 eV
• La 4p: 16.9 eV

The Energies Listed are Binding Energies!

• La 3p:1125 eV
• La 3d: 834.2 eV
• La 4s: 275 eV
• La 4p: 194 eV
• La 4d: 98 eV
• La 5s: 35 eV

The Energies Listed are Binding Energies!

Sb is primarily analyzed via the 3d orbital

• Te 3p3/2 (819 eV)
• In 3s (826 eV)
• Ce LMM (Al source) (828 eV)
• F KLL (Al source) (842 eV)
• Tl 4s (846 eV)
• Fe 2s (846 eV)
• Po 4p (851 eV)
• Ni 2p (855 eV)
• La MNN (Al source) (865 eV)

Energies listed are Kinetic Energies!

La MNN: ~ 622 eV

Lanthanum metal consists of a typical asymmetric doublet with a spin-orbit separation of 17 eV.⁽¹⁾

Note for below: WordPress does not support underlining characters – so core holes will be described using a bold text-type rather than an underlined text-type. Apologies for the confusion.

Lanthanum compounds however, undergo peak splitting and each spin-orbit coupled peak appears as a doublet (Figure 1). In general, this is due to the formation of one poorly screened final state (ground state – 4fⁿ(3dⁿ) – cf⁰) and one well-screened final state due to conduction band to 4f charge transfer screening (4fⁿ⁺¹(3dⁿ⁺¹⁺) – cf¹L).⁽²⁾

Analysis of lanthanum by XPS is typically performed on the 3d orbitals, which may overlap with Fe 2s, In 3s as well as the KLL auger from flourine and the Ce LMM auger if using Al X-rays (1486.7 eV). Additionally, the La M_4,5N_4,5N_4,5 auger overlaps with the La 3d peaks when using Al X-rays which may complicate peak analysis (can be separately modeled using a twin X-ray source).

Lanthanum oxide is prone to carbonate formation, and as such, heating in vacuo may be required to remove any carbonate layer prior to analysis.

Figure 1: La₂O₃ (green) and Lanthanum acetate sesquihydrate (red)⁽³⁾

The energy separation between the two maxima changes between the oxide and hydroxide, and in fact is often used as a simple method for determining chemical state (Table 1).⁽⁵⁾

Table 1: Peak separation energies for lanthanum oxide and hydroxide

Interestingly, no spin orbit splitting may be observed for the La 4p region due to a Coster-Kronig process⁽⁸⁾ but further splittings enable this region to be of use when dealing with lanthanum in XPS (Figure 3).⁽⁴⁾