The method is based on the analysis of the distribution of the binding energies of the photoelectrons, emitted by the studied material upon excitation with ultraviolet radiation (ultraviolet photoelectron spectroscopy: UPS), or with X-ray radiation (X-ray photoelectron spectroscopy: XPS). If the distribution of the emission angles of the photoelectrons is also measured, the technique is called angle-resolved (angle-resolved photoelectron spectroscopy: ARPES)

XPS method, based on the excitation of core-level electrons, enables studying the chemical composition of materials. Because it is semi-quantitative, it allows to determine the stoichiometry of complex compounds. Chemical shifts of the emission maxima can be used to study the chemical environment of different atoms in the samples (type of chemical bonds, oxidation level). UPS method, based on the excitation of valence electrons, especially in the angle-resolved variant, allows for studying the electronic structure of various materials near the Fermi energy.

The method is surface-sensitive and the signal is collected from the layer with the depth of up to a few nanometers. Surface sensitivity can be increased, by tilting the sample, or by varying incoming photon energy. Under optimal circumstances, it is possible to obtain signal from a single atomic layer of the studied material. 

PS method can be used in the following industries:

• steel and non-ferrous metals (surface composition of metals undergoing various treatments, studying corrosion and aging mechanisms)
• thin films (composition and depth profiling)
• catalysis (chemical environment of the catalytic active sites, time-resolved studies, ageing and regeneration of catalysts)
• electronics and spintronics (electronic structure of semiconductors and metals, properties of the metal-semiconductor or semiconductor-insulator junctions, identification of surface states and resonances, Fermi level pinning)
• low dimensional materials (electronic structure of 2D materials, e.g. graphene, composition and stoichiometry of the materials, depth profiling of multi-layer materials).

PS method is available on the following beamlines: URANOS and PHELIX . The basic parameters of the experimental stations and restrictions with regard to sample type are shown in table.