Analysis of X-ray adsorption edges: L 2,3 edge of FeCl 4 .

We describe a detailed analysis of the features of the X-ray adsorption spectra at the Fe L _2,3 edge of FeCl ₄ ^- . The objective of this analysis is to explain the origin of the complex features in relation to properties of the wavefunctions, especially for the excited states. These properties include spin-orbit and ligand field splittings where a novel aspect of the dipole selection rules is applied to understand the influence of these splittings on the spectra. We also explicitly take account of the intermediate coupling of the open core and valence shell electrons. Our analysis also includes comparison of theory and experiment for the Fe L _2,3 edge and comparison of theoretical predictions for the Fe ³⁺ cation and FeCl ₄ ^- . The electronic structure is obtained from theoretical wavefunctions for the ground and excited states.