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

N. El Hassan (1) , J. M. Bizau (1) , Christophe Blancard (2, 3) , Philippe Cossé (2) , D. Cubaynes (1) , Gérald Faussurier (2) , F. Folkmann (4)

1 LIXAM - Laboratoire d'interaction du rayonnement X avec la matière
2 DAM/DIF - DAM Île-de-France
3 LUTH (UMR_8102) - Laboratoire Univers et Théories
4 DASC - Danish AsteroSeismology Centre

We 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.

Domaines: Astrophysique [astro-ph]

N. El Hassan, J. M. Bizau, Christophe Blancard, Philippe Cossé, D. Cubaynes, et al.. Photoionization cross sections of iron isonuclear sequence ions: Fe2+ to Fe6+. Physical Review A, 2009, 79, pp.33415. ⟨10.1103/PhysRevA.79.033415⟩. ⟨hal-03733005⟩