Chemical bonding effects in Sc compounds studied using X-ray absorption and X-ray photoelectron spectroscopies

Abstract

Advances on understanding the nature of the chemical bonding and electron correlation effects during the X-ray absorption process in ionic–covalent metal complexes has been achieved for most of the transition elements, except for scandium, due to the lack of a systematic series of spectroscopic reference spectra and the shortage of standard crystallographic data on scandium compounds. To close the gap, the chemical bonding effects in eight Sc compounds are studied using X-ray absorption spectroscopy (XAS) at Sc K and L_2,3 absorption edges and X-ray photoelectron spectroscopy (XPS). Indeed, the fine structure of the XAS Sc K edge reflects the chemical sp³-like bond formed between scandium and the ligand while the L_2,3 edge and the pre-edge features of the K-edge provide a direct insight into the crystal field parameters at the Sc site in the coordination compound. The XPS data provide the information on binding energies of the core electrons involved in the electron transitions caused by the absorption of high energy X-rays. XAS and XPS complement each other by accessing the information on Sc structure on bulk and the surface. Herein, comprehensive information on the electronic structure of well-known crystalline materials based on Sc is given with spectroscopic fingerprints X-ray data. This will help to predict the formation of chemical bonds in the unknown components via the systematic evaluation of the available spectroscopic fingerprints.