The iron L edges: Fe 2p X-ray absorption and electron energy loss spectroscopy

Abstract

The iron L edges are reviewed. The experimental spectra obtained with 2p XAS, XMCD and 2p EELS are discussed, including isolated iron atoms, solids and coordination compounds. The largest fraction of publications deal with iron oxide systems that are discussed in detail, including binary oxides, perovskites and spinel systems. Emphasis is given on fundamental studies that focus on spectral shape analysis. We have selected a number of applications for further discussion, including iron in astrochemistry, iron complexes and nanostructures in catalysis, iron in mineralogy, the pnictide superconductors, spin cross-over systems and phthalocyanine and related systems.Some of the important theoretical concepts in the analysis of L edges are discussed, including atomic multiplet theory, crystal field theory, charge transfer theory and XMCD. The 2p XAS spectra contain much detail for halides, oxides and coordination compounds. These spectra can be analyzed in great detail, revealing much information, including the valence, the spin state and the crystal field parameters. Covalent compounds and metal alloys have spectra with much less detail, which makes analysis more difficult.