High-resolution X-ray Absorption and Emission Spectroscopic Characterization of High-Valent Copper Ions

In recent years, a fundamental debate over the spectroscopic signatures- and by extension the very existence- of Cu(III) centers has emerged. We have recently validated the interpretation of Cu(III) as a formal oxidation in molecular complexes in a detailed X-ray absorption and Valence-to-Core emission (VtC XES) study. Our recent work motivates us to further explore not only other debated Cu(III) centers, but also to push towards even higher oxidation-states. For several decades now, cesium hexafluoridecuprate (Cs2CuIVF6) has been the only know example of a formal Cu(IV) ion; however, it lacks spectroscopic investigation. We will measure the Cu XAS and XES signatures of a series of copper fluoride salts in various oxidation states to provide some of the rarest examples of high-valent copper spectroscopy.