Correlation of electronic structures and stabilities of gaseous FeI2, Fe2I2 and Fe2I4 molecules, solid 〈FeI2〉, and iodine adsorbed on 〈Fe〉

The equilibrium gas phase above solid iron(II) iodide, the pure solid phase 〈FeI2〉, and iodine adsorbed on iron (100) surfaces have been studied by electron-impact ionization in combination with high-temperature mass spectrometry, photoionization using synchrotron radiation, and by photoelectron spectroscopy (XPS and UPS). The acquired data on bond stabilities and orbital energy shifts of Fe and II2 in varying chemical and spatial environments provide detailed insight into the energetics and electronic structure of the iron/iodine system. Special attention has been given to the gaseous dimers Fe2I2(g) and Fe2I4(g), the first members of a series of clusters which bridge the gap between the gaseous monomers FeI(g)FeI2(g) and the condensed phases 〈FeI2〉 and the (hypothetical) iron(I) iodide 〈FeI〉.