Issue 21, 2013

The chemical sensitivity of X-ray spectroscopy: high energy resolution XANESversusX-ray emission spectroscopy of substituted ferrocenes

Abstract

X-ray spectroscopy at the metal K-edge is an important tool for understanding catalytic processes and provides insight into the geometric and electronic structures of transition metal complexes. In particular, X-ray emission-based methods such as high-energy resolution fluorescence detection (HERFD), X-ray absorption near-edge spectroscopy (XANES) and valence-to-core X-ray emission spectroscopy (V2C-XES) hold the promise of providing increased chemical sensitivity compared to conventional X-ray absorption spectroscopy. Here, we explore the ability of HERFD-XANES and V2C-XES spectroscopy to distinguish substitutions beyond the directly coordinated atoms for the example of ferrocene and selected ferrocene derivatives. The experimental spectra are assigned and interpreted through the use of density functional theory (DFT) calculations. We find that while the pre-edge peaks in the HERFD-XANES spectra are affected by substituents at the cyclopentadienyl ring containing π-bonds [A. J. Atkins, Ch. R. Jacob and M. Bauer, Chem.–Eur. J., 2012, 18, 7021], the V2C-XES spectra are virtually unchanged. The pre-edge in HERFD-XANES probes the weak transition to unoccupied metal d-orbitals, while the V2C-XES spectra are determined by dipole-allowed transitions from occupied ligand orbitals to the 1s core hole. The latter turn out to be less sensitive to changes beyond the first coordination shell.

Graphical abstract: The chemical sensitivity of X-ray spectroscopy: high energy resolution XANES versus X-ray emission spectroscopy of substituted ferrocenes

Supplementary files

Article information

Article type
Paper
Submitted
06 Mar 2013
Accepted
22 Mar 2013
First published
12 Apr 2013

Phys. Chem. Chem. Phys., 2013,15, 8095-8105

The chemical sensitivity of X-ray spectroscopy: high energy resolution XANES versus X-ray emission spectroscopy of substituted ferrocenes

A. J. Atkins, M. Bauer and C. R. Jacob, Phys. Chem. Chem. Phys., 2013, 15, 8095 DOI: 10.1039/C3CP50999K

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