Lanthanum

Lanthanum • Lanthanide Rare Earth

Primary XPS region: La3d
Overlapping regions: Transition metal Augers, La MNN
Binding energies of common chemical states:

Chemical state	Binding energy La3d_5/2
La₂O₃	834.5 eV
La(OH)₃	834.7 eV
La₂(CO₃)₃	835 eV

Experimental information

La3d is the primary XPS region, but La4p and La4d regions can help assign the chemistry of lanthanum compounds.

Interpretation of XPS spectra

La3d region has well-separated spin-orbit components.
- Each spin-orbit component is further split by multiplet splitting.
- For example, the La3d spectrum from a pure La(OH)₃ sample will have four visible components, even though there is only one chemical state.

The magnitude of the multiplet splitting and intensity ratio of each multiplet-split component are chemically diagnostic.

Inspection of the La4p region can also help assign chemistry, e.g. differentiating between La₂O₃ and La(OH)₃.

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General comments

La₂O₃ has an unusually low O1s binding energy of ~528.6eV.
- Metal oxides more typically appear at 530eV.
La is highly reactive, so La is usually found in an oxidized state.
La compounds may hydrolyze and/or react with CO₂ to form surface carbonates.

About this element

Symbol: La
Date of discovery: 1839
Name origin: Greek lanthanein
Appearance: white
Discoverer: Carl Gustaf Mosander
Obtained from: monazite, bastnasite

Melting point: 1193 K
Boiling point: 3743 K
Density[kg/m³]: 6146
Molar volume: 22.39 × 10^-6 m³/mol
Protons/Electrons: 57
Neutrons: 82
Shell structure: 2,8,18,18,9,2
Electron configuration: [Xe]5d16s2
Oxidation state: 3
Crystal structure: hexagonal

This element is so soft that it can be cut by a knife. Lanthanum has an important role in the motion picture industry because it is used in studio lighting and projection. It is also used to make infrared absorbing glass and is used in the lenses of cameras and telescopes. Adding small amounts of lanthanum to steel improves steel’s malleability and adding it to molybdenum decreases molybdenum’s hardness and sensitivity to temperature variation. While lanthanum has no known biological role, lanthanum chloride has anticoagulant properties. Injecting lanthanum solutions in animals causes glycohemia, low blood pressure, degeneration of the spleen, and hepatic alterations.

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