URANOS beamline (Ultra Resolved ANgular phOtoelectron Spectroscopy beamline) allows for measurements of fundamental quantities, i.e. the energy and the momentum, describing a photoelectron state in the space outside the solid sample.

If a spin selector is used additionally, a complete set of quantum numbers for the electron may be obtained. Then, within a so called sudden approximation, the electron energy, momentum and spin measured over the sample surface may be related, to binding energy, quasimomentum, and spin, that the electron had in the solid before the photoelectric event took place. Thus the electronic band structure of the studied solid is obtained experimentally. Beside this simple picture ARPES gives also detailed insights into complex electron – electron and electron – lattice interactions in the solid.

The importance of the ARPES technique for contemporary science and technology is widely recognized. Dedicated ARPES beamlines exist at almost all synchrotron radiation centers worldwide.

Many recent advances in materials science have been enabled by better understanding of the electronic structure of complex systems, gained due to ARPES studies. Examples include advances in fields such as:

• high temperature superconductivity
• topological insulators
• graphene physics.