X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in γ-Al2O3

Abstract

The 2–4 keV energy range provides a rich window into many facets of materials science and chemistry. Within this window, P, S, Cl, K and CaK-edges may be found along with theL-edges of industrially important elements from Y through to Sn. Yet, compared with those that cater for energies aboveca.4–5 keV, there are relatively few resources available for X-ray spectroscopy below these energies. In addition,in situoroperandostudies become to varying degrees more challenging than at higher X-ray energies due to restrictions imposed by the lower energies of the X-rays upon the design and construction of appropriate sample environments. The XMaS beamline at the ESRF has recently made efforts to extend its operational energy range to include this softer end of the X-ray spectrum. In this report the resulting performance of this resource for X-ray spectroscopy is detailed with specific attention drawn to: understanding electrostatic and charge transfer effects at the SK-edge in ionic liquids; quantification of dilution limits at the ClK- and RhL3-edges and structural equilibria in solution; in vacuum deposition and reduction of [RhI(CO)2Cl]2to γ-Al2O3; contamination of γ-Al2O3by Cl and its potential role in determining the chemical character of supported Rh catalysts; and the development of chlorinated Pd catalysts in `green' solvent systems. Sample environments thus far developed are also presented, characterized and their overall performance evaluated.