Electronic structure

Identifying the organisation of electrons in matter.

Electronic structure defines how electrons organise within matter. It provides vital insights into the origin of physical properties down to the atomic scale. Quantifying electronic structure experimentally can be used to define atomic electron configurations, oxidation state, the type of chemical bonds, the coordination symmetry of bound atoms and the quantum spin and orbital contributions to magnetic properties.

Our research group specialises in the application of both X-ray and inelastic neutron spectroscopies for the study of electronic structure. We apply a broad range of X-ray techniques including X-ray absorption near-edge fine structure (XANES), X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS). We apply dichroism for some of these methods, including X-ray magnetic circular dichroism (XMCD) and X-ray linear dichroism. It is an important part of our research to back experimental results with theoretical simulations. This enables us to obtain a fundamental understanding of experimental sensitivities to electronic structure and facilitates precise quantification of physical properties.

We utilise atomic multiplet theory, time-dependent density functional theory and ab. initio. quantum chemistry methods to simulate spectra and identify precise descriptions of electronic structure. 

X-ray spectroscopy

X-ray absorption spectroscopies are ideally suited for accessing electronic structure since by tuning the x-ray energy it is possible to measure the excitation of core-electrons into the lowest energy unoccupied orbitals.

Since the absorption edge energy is specific for any given element, element-specific electronic structure can be obtained in crystalline and non-crystalline environments. X-ray absorption spectroscopy can therefore provide important information concerning the electronic and geometric structure of an analyte in solid, liquid or even gaseous forms.

Combining X-ray absorption with emission spectroscopy makes it possible to measure both the lowest energy unoccupied orbitals and the highest energy occupied orbitals, providing a holistic picture of the frontier molecular orbitals or Fermi level.    

Inelastic neutron spectroscopy

Neutrons have a quantum spin of a half but carry no charge and are therefore highly penetrating in matter. We apply inelastic neutron scattering to study the spin dynamics of molecular-based magnetic compounds. 

Our research

Actinide chemical properties for effective geological disposal of nuclear waste

We are interested in obtaining an accurate understanding of actinide structure-function relationships. To achieve this we combine advanced synchrotron X-ray spectroscopy methods (RIXS, XANES, XES, XMCD) with semi-empirical and ab. initio. theories. We focus on simple periodic trends to systematically investigate how symmetry, oxidation state and ligand atom influence properties. See, for instance, J. Am. Chem. Soc. 2024, 146, 32, 22570–22582 (https://doi.org/10.1021/jacs.4c06869)

Electrons in atoms and molecules for quantum technologies

We are interested in how unusual oxidation states and electronic configurations can be exploited to tailor electronic structure and paramagnetism. We apply neutron and X-ray spectroscopies to correlate structures to spin dynamics in molecules and dopants in crystals and on surfaces. See, for instance, Chem. Sci., 2024,15, 2433-2442 (https://doi.org/10.1039/D3SC06308A)

Bio-inorganic chemistry: catalysis at transition metal active sites

We apply advanced X-ray spectroscopies to quantify metal-ligand covalency in various bio-inorganic systems with active Fe, Co, and Cu sites. See, for instance, J. Am. Chem. Soc. 2023, 145, 34, 18977–18991 (https://doi.org/10.1021/jacs.3c06181)