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

► 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.