2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/7114We study the ionization equilibrium of Fe using photoionization models that incorporate improved values for the ionization and recombination cross-sections and the charge-exchange rates for the Fe ions. The previously available photoionization models predict concentrations of Fe3+ which are a factor of 3-8 higher than the values inferred from emission lines of [Fe III] and [Fe IV]. Our new models reduce these discrepancies to factors of 2-5. We discuss the possible reasons behind the remaining discrepancies and present an updated ionization correction factor for obtaining the Fe abundance from the Fe++ abundance.4 pages, 1 figure, extended version of the paper to be published in "Recycling intergalactic and interstellar matter", IAU Symposium Series, Vol. 217, 2004, P.-A. Duc, J. Braine and E. Brinks, edsAstrophysicstext