Inner-shell excitation spectroscopy of peroxides

The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3 ]. Angew Chem Int Ed Engl 2022;61:e202207688. [PMID: 35818987 PMCID: PMC9544489 DOI: 10.1002/anie.202207688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Although the highest possible oxidation states of all transition elements are rare, they are not only of fundamental interest but also relevant as potentially strong oxidizing agents. In general, the highest oxidation states are found in the electron-rich late transition elements of groups 7-9 of the periodic table. Rhodium is the first element of the 4d transition metal series for which the highest known oxidation state does not equal its group number of 9, but reaches only a significantly lower value of +6 in exceptional cases. Higher oxidation states of rhodium have remained elusive so far. In a combined mass spectrometry, X-ray absorption spectroscopy, and quantum-chemical study of gas-phaseR h O n + (n=1-4), we identifyR h O 3 + as the1 A 1 ' trioxidorhodium(VII) cation, the first chemical species to contain rhodium in the +7 oxidation state, which is the third-highest oxidation state experimentally verified among all elements in the periodic table.

X-ray Raman Scattering: A Hard X-ray Probe of Complex Organic Systems

This paper provides a review of the characterization of organic systems via X-ray Raman scattering (XRS) and a step-by-step guidance for its application. We present the fundamentals of XRS required to use the technique and discuss the main parameters of the experimental set-ups to optimize spectral and spatial resolution while maximizing signal-to-background ratio. We review applications that target the analysis of mixtures of organic compounds, the identification of minor spectral features, and the spatial discrimination in heterogeneous systems. We discuss the recent development of the direct tomography technique, which utilizes the XRS process as a contrast mechanism for assessing the three-dimensional spatially resolved carbon chemistry of complex organic materials. We conclude by exposing the current limitations and provide an outlook on how to overcome some of the existing challenges and advance future developments and applications of this powerful technique for complex organic systems.

Influence of Local Environment on Inner Shell Excitation Spectra, Studied by Electron and X-ray Spectroscopy and Spectromicroscopy

Inner shell excitation spectroscopy is a local probe of the unoccupied electronic structure in the immediate vicinity of the core excited atom. As such, one might expect the inner shell spectrum of a given unit (a molecular fragment or a repeat unit of a solid) to be largely independent of where that unit is located. This is often an implicit assumption in spectral analysis and analytical applications. However, there are situations where inner shell excitation spectra exhibit significant sensitivity to their local environment. Here I categorize the ways in which inner shell spectra are affected by their local environment, and give examples from a career dedicated to developing a better understanding of inner shell excitation spectroscopy, its experimental techniques, and applications.