Copper

Copper • Transition Metal

Primary XPS region: Cu2p
Overlapping regions: Pr3d
Binding energies of common chemical states:

Chemical state	Binding energy Cu2p_3/2
Cu metal	933 eV
Cu(I) oxide	933 eV
Cu(II) oxide	~933.5 eV
Cu(II) carbonate dihydroxide	934.7 eV

Experimental information

Collect principal Cu LMM peak as well as Cu2p.
- Bigger chemical shifts observed for Cu LMM compared to Cu2p.
- Chemical state differentiation can be difficult with XPS only.
Long X-ray exposure or ion bombardment can reduce or degrade Cu(II) compounds. Sputter with Ar clusters and/or minimize X-ray exposure to prevent this effect.

Interpretation of XPS spectra

Cu2p peak has significantly split spin-orbit components (Δ=19.75eV, intensity ratio=0.508).
- It is possible to distinguish Cu oxidation states using satellite features of Cu2p.
- Cu(II) has an observable collection of satellite features at 943eV.
- Cu2p_3/2 peak in Cu(II) oxide is shifted and is much broader compared to Cu(I) oxide.
In Cu(I) oxide, there is only a very weak satellite at 945eV.
Cu2p_3/2 peak in Cu(I) oxide is NOT shifted, but is broader compared to Cu metal.

There are small binding energy shifts of some compounds compared to copper metal.
- Chemical state differentiation can be difficult with XPS only.
- Collect principal Cu LMM peak, as well as Cu2p. There are bigger chemical shifts observed for Cu LMM compared to Cu2p.
- Use Wagner plot to help assign chemistry.

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Table of elements

About this element

Symbol: Cu
Date of discovery: ancient
Name origin: Latin cyprium
Appearance: red/orange
Discoverer: unknown
Obtained from: chalcopyrite, coveline, chalcosine

Melting point: 1358 K
Boiling point: 2927 K
Density[kg/m³]: 8.96
Molar volume: 7.11 × 10^-6 m³/mol
Protons/Electrons: 29
Neutrons: 35
Shell structure: 2,8,18,1
Electron configuration: [Ar]3d104s1
Oxidation state: 3,1
Crystal structure: cubic

Playing a significant role in history for at least 10,000 years, copper is reddish in color and has high electrical and thermal conductivity. Copper has many household uses, including wires, doorknobs and other fixtures, plumbing, roofing, and cookware products. Most American coins are largely comprised of this element, while the Statue of Liberty contains 179,200 pounds of copper. It is also used to make several musical instruments, especially brass instruments and cymbals. Copper is essential to all higher plants and animals and is transported mainly in the bloodstream.

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