Palladium

Palladium • Transition Metal

Primary XPS region: Pd3d
Overlapping regions: Ca2p, Au4d_5/2
Binding energies of common chemical states:

Chemical state	Binding energy Pd3d_5/2
Pd metal	335.0 eV
Native oxide	336.7 eV

Experimental information

Pd oxide reduces with X-ray exposure.
- Acquire Pd3d region before all others, if possible.
- Minimize acquisition time for Pd3d region.

Interpretation of XPS spectra

Pd3d region has well-separated spin-orbit components (Δ=5.26eV).
Pd3d peaks have asymmetric peak shapes for metals.
- Pd oxide has symmetric peak shapes.
Direct overlap between Pd3p_3/2 and O1s peaks.
- Use Pd3p_1/2, which does not overlap with O1s, as a guide for any peak fitting.
- Intensity and binding energy of Pd3p_3/2 peak is set by the Pd3p_1/2 peak, according to the spin-orbit splitting and ratio.
- Remainder of intensity under at Pd3p_3/2, energy can then be attributed to oxygen.

About this element

Symbol: Pd
Date of discovery: 1803
Name origin: Greek pallas
Appearance: white
Discoverer: William Wollaston
Obtained from: platinum, nickel, copper, mercury ores

Melting point: 1825 K
Boiling point: 3200 K
Density[kg/m³]: 12023
Molar volume: 8.56 × 10^-6 m³/mol
Protons/Electrons: 46
Neutrons: 60
Shell structure: 2,8,18,18,0
Electron configuration: [Kr]4d10
Oxidation state: ±1
Crystal structure: cubic face centered

Primarily used as an industrial catalyst and in jewelry, palladium is a rare silver-white transition metal similar to platinum. Some notable features of palladium include its tarnish resistance, low density and melting point, and its chemical attraction to sulfuric and nitric acid. When dissolved in hydrochloric acid, palladium absorbs up to 900 times its own volume of hydrogen at room temperature. Palladium was first discovered in 1803 in crude platinum ore from South America by W. H. Wollaston. Palladium was named after the asteroid Pallas, which was discovered two years prior to the element’s discovery. Palladium is commercially-produced from nickel-copper deposits. The element can be found as a free metal and alloyed within platinum and gold in deposits located in Ethiopia, South and North America, and the Ural Mountains.