X-ray Absorption Spectroscopy (XAS) has been used extensively to probe both the electronic and geometric structure of metal sites. The technique is element specific, meaning that it can be used to probe the electronic transitions of metal sites rather than those due to ligands or the surrounding environment. XAS can be applied to several types of studies including K-edge, L-edge and EXAFS (Extended X-ray Absorption Fine Structure). Metal L-edge spectroscopy specifically probes the unoccupied metal d-orbitals looking at 2p to 3d transitions that are dipole allowed.

Most L-edge spectra are currently collected at the Stanford Synchrotron Radiation Laboratory (SSRL) in the solid phase under ultra high vacuum and at high concentrations. Spectroscopic results are then analyzed by computational methods such as DFT and various multiplet simulations.

New spectroscopic techniques are also currently under development to allow for the study of samples in either the liquid phase or under normal atmosphere as complexes which contain bound dioxygen decompose under UHV.

The overall goal of the project is to further scientific understanding of iron bonding in heme vs. non-heme systems, thereby refining the current L-edge methodology and providing important insights into the electronic structure, reactivity, and chemical bonding of various families of iron enzymes and model complexes.