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Computational EPR Spectroscopy of Randomly Oriented Materials
Randomly oriented materials in form of powders, glasses or frozen solutions give rise to EPR spectra that usually are not easily amenable to direct quantitative analysis. In addition low symmetry environments often encountered in disordered heterogeneous systems can further complicate the spectra. Under such circumstances advanced computer analysis of the EPR spectra is the only method suitable for accurate extraction of the spin Hamiltonian parameters, allowing for their subsequent in-depth molecular interpretation. Computational EPR spectroscopy provides a combination of a hybrid genetic algorithm for robust and efficient simulation of complex experimental EPR spectra with density functional theory (DFT) calculations of magnetic parameters (g and A tensors or zero-field splitting). This approach can be used for guiding interpretation of the EPR data of large molecular and reticular paramagnetic systems characterized by complex structure, profound speciation, and low symmetry features. Appropriate level of theory of the relativity treatment along with careful selection of the exchange-correlation functional are indispensable for obtaining sensible results. In this paper various aspects of computational EPR spectroscopy will be discussed and illustrated using examples coming from our laboratory.
Zbigniew Sojka
- Professor of Chemistry
- Head of the Catalysis and Solid State Group
- Faculty of Chemistry, Department of Inorganic Chemistry,
- Jagiellonian University
Research profile
Materials and Surface Chemistry; Heterogeneous Catalysis; Molecular Modeling; Electron Paramagnetic Resonance and Transmission Electron Microscopy techniques
The research interest is focused on synthesis, spectroscopic characterization and reactivity studies of nanostructured and porous inorganic materials, which are functionalized with transition metal ions for guiding surface reactions along specific pathways. In our methodology we combine various spectroscopic techniques, high resolution electron microscopy with quantum chemical calculations, including ab initio thermodynamic and microkinetic modeling. We design and investigate model systems of controlled electronic and magnetic structure with tunable redox properties for establishing quantitative structure-property-function relationships, and elucidation of catalytic reaction mechanisms with particular insights into interfacial charge and spin transfer processes.