Cadmium

Cadmium • Transition Metal

Primary XPS region: Cd3d
Overlapping regions: N1s, Hf4p_1/2, Sc2p
Binding energies of common chemical states:

Chemical state	Binding energy Cd3d_5/2
Cd metal	405.1 eV
CdS	405.1 eV

Experimental information

Small binding energy shifts of some compounds compared to cadmium metal.
- Chemical state differentiation can be difficult with XPS only.
- Collect principal Cd MNN peak as well as Cd3d.
  - Bigger chemical shifts observed for Cd MNN compared to Cd3d.

Interpretation of XPS spectra

Cd3d region has well separated spin-orbit components (Δ_metalsub>=6.8eV).
- Peaks have asymmetric peak shape for metal.
- Loss features are observed to higher binding energy side of 3d_3/2 spin-orbit component for Cd metal.

Small or negligible binding energy shifts for compounds, such as oxides or sulfide.
- Cd3d peaks broaden with respect to metal peaks for compounds..
- Use X-ray-induced Cd MNN Auger peaks to aid chemical state assignment.

About this element

Symbol: Cd
Date of discovery: 1817
Name origin: Greek kadmeia
Appearance: silvery
Discoverer: Fredrich Stromeyer
Obtained from: by-product, zinc refining

Melting point: 320.9 K
Boiling point: 765 K
Density[kg/m³]: 8.65
Molar volume: 13.00 × 10^-6 m³/mol
Protons/Electrons: 48
Neutrons: 64
Shell structure: 2,8,18,18,2
Electron configuration: [Kr]4d105s2
Oxidation state: 2
Crystal structure: hexagonal

This very soft metal is often found as an impurity in zinc. After being discovered in Germany in 1817, cadmium was mainly produced in that country for the next 100 years. Although highly toxic, cadmium and its compounds were used as a medication to treat several illnesses in the early 1900’s. Today, cadmium is recognized as a cause of several types of cancer. Cadmium poisoning is called itai-itai disease in Japan (literally "ouch ouch" disease) due to the severe pain it causes. Cadmium is used in batteries, pigments, coatings and plating, and is used as a stabilizer for plastics.