Abstract
An R-matrix LS-coupling calculation of the photoionization of neutral iron is presented, in which the 17 terms with configurations 3d7, 3d5(6S)4s2, 3d6(5D)4s and 3d6(5D)4p are included in the Fe+ core. the photoionization cross section for excited states of Fe show large broad resonances, known as PEC resonances, which arise due to photoexcitation of the core. The mechanism is illustrated for the 3d6(5D)4snd 7Se series in Fe, where the photon is absorbed by a 4s4p transition in the Fe+ core with the nd electron acting as a spectator, forming autoionization resonances below the 3d6(5D)4p thresholds.