Photoionization cross sections of iron isonuclear sequence ions: Fe2+ to Fe6+

International audienceWe have measured the absolute photoionization cross sections of Fe2+ to Fe6+ ions in the photon energy range covering the first ionization threshold up to 160 eV. Particular interest is emphasized on the region of the 3p-->3d excitations. The experimental data are compared to the results of calculations we have performed using a spectral opacity code, as well as to available R -matrix and one-electron calculations. It is shown that often the theoretical results tend to overestimate the intensity of the 3p-->3d photoexcitations. An anomalously low value of the integrated oscillator strength is measured for Fe2+ ion