Relative sub-shell photoionization cross-sections of nickel metal determined by hard X-ray high kinetic energy photoemission

Highlights: ► We determined for the first time photoionization cross sections of Ni 3s and 3p. ► The experimental cross sections were measured within 2–9 keV excitation energy. ► Good agreement of data obtained through two different experimental approaches found. ► Good agreement of the measured 3p values and the Scofield theoretical cross section. ► Baffling difference of the measured 3s values compared to theoretical ones. -- Abstract: Recently, hard X-ray high kinetic energy photoelectron spectroscopy has lead to a break-through due to its non destructive way of investigating the bulk electronic properties of materials. However, due to the relatively new development of this technique there is a lack of information concerning the photoionization cross sections at high energies. Whenever compound materials are investigated or when estimating signal levels and the feasibility of an electron spectroscopy experiment the knowledge of cross sections is essential. In the present work the experimentally determined relative sub-shell photoionization cross sections of shallow levels of nickel metal in the energy range of 2–9 keV will be shown. The data are compared with calculated sub-shell photoionization cross sections