Simultaneous two-color X-ray absorption spectroscopy using Laue crystals at an inverse-compton scattering X-ray facility.

Juanjuan Huang,Martin Dierolf,Klaus Achterhold,Benedikt Günther,Franz Pfeiffer

doi:10.1107/s1600577521009437

Abstract

X-ray absorption spectroscopy (XAS) is an element-selective technique that provides electronic and structural information of materials and reveals the essential mechanisms of the reactions involved. However, the technique is typically conducted at synchrotrons and usually only probes one element at a time. In this paper, a simultaneous two-color XAS setup at a laboratory-scale synchrotron facility is proposed based on inverse Compton scattering (ICS) at the Munich Compact Light Source (MuCLS), which is based on inverse Compton scattering (ICS). The setup utilizes two silicon crystals in a Laue geometry. A proof-of-principle experiment is presented where both silver (Ag) and palladium (Pd) K-edge X-ray absorption near-edge structure spectra were simultaneously measured. The simplicity of the setup facilitates its migration to other ICS facilities or maybe to other X-ray sources (e.g. a bending-magnet beamline). Such a setup has the potential to study reaction mechanisms and synergistic effects of chemical systems containing multiple elements of interest, such as a bimetallic catalyst system.

Highlights

Bimetallic catalysts, which consist of two metal components rather than a single host metal, form a major class of heterogeneous catalysts (Somorjai & Li, 2010; Tao, 2012)
Silver–palladium (Ag–Pd) bimetallic catalysts have been used for catalytic processes such as hydrogenation (Choi et al, 2019; Tedsree et al, 2011; Zhang et al, 2000), dehydrogenation (Guo et al, 2003; Huang et al, 2010), oxidation (Tou et al, 2019) and reduction reactions (Li et al, 2016)
We present a two-color X-ray absorption spectroscopy (XAS) setup based on two Laue crystals at the Munich Compact Light Source (MuCLS) facility

Summary

Introduction

Bimetallic catalysts, which consist of two metal components rather than a single host metal, form a major class of heterogeneous catalysts (Somorjai & Li, 2010; Tao, 2012). The limited access to the large facilities and constantly oversubscribed beam time (for example, the oversubscription for all beamlines at the European Synchrotron Radiation Facility was 275% in 2018 according to its annual highlight report of 2019) prevent XAS/ XES experiments from being conducted on a routine basis For this reason, the last decade has witnessed intensive and significant development of modern laboratory XAS/XES setups using X-ray tubes (Seidler et al, 2014; Nemeth et al, 2016; Bes et al, 2018; Błachucki et al, 2019; Ditter et al, 2019; Schlesiger et al, 2020; Zeeshan et al, 2020). Combination with our ongoing efforts in in situ XAS developments at our ICS facility on campus (Huang et al, 2021), which is especially advantageous when sample transfer to synchrotron facilities is challenging or multiple iterations of an experiment are necessary, the proposed setup may unravel new opportunities for studying interaction mechanisms — time-resolved or in situ — between multimetallic sites involved in catalytic processes

Experimental

Results and discussion

Conclusion

Findings

Funding information