An improved laboratory-based x-ray absorption fine structure and x-ray emission spectrometer for analytical applications in materials chemistry research

Abstract

X-ray absorption fine structure (XAFS) and x-ray emission spectroscopy (XES) are advanced xray spectroscopies that impact a wide range of disciplines. However, unlike the majority of other spectroscopic methods, XAFS and XES are accompanied by an unusual access model, wherein; the dominant use of the technique is for premier research studies at world-class facilities, i.e., synchrotron x-ray light sources. In this paper we report the design and performance of an improved spectrometer XAFS and XES based on the general conceptual design of Seidler, et al., Rev. Sci. Instrum. 2014. New developments include reduced mechanical degrees of freedom, much-increased flux, and a wider Bragg angle range to enable extended x-ray absorption fine structure (EXAFS) for the first time with this type of modern laboratory XAFS configuration. This instrument enables a new class of routine applications that are incompatible with the mission and access model of the synchrotron light sources. To illustrate this, we provide numerous examples of x-ray absorption near edge structure (XANES), EXAFS, and XES results for a variety of problems and energy ranges. Highlights include XAFS and XES measurements of battery electrode materials, EXAFS of Ni and V with full modeling of results to validate monochromator performance, valence-to-core XES for 3d transition metal compounds, and uranium XANES and XES for different oxidation states. Taken en masse, these results further support the growing perspective that modern laboratory-based XAFS and XES have the potential to develop a new branch of analytical chemistry.

Interface Engineering V2O5 Nanofibers for High‐Energy and Durable Supercapacitors

“…The concentration of each oxidation state of vanadium cations was estimated from the corresponding peak area percentage. The overall vanadium oxidation states of the samples were examined by X‐ray absorption near‐edge structure measurements in the vanadium K‐edge using laboratory‐based instrumentation (University of Washington), and analyzed with a reported methodology . Fitting was performed in Mathematica with the energy from 5460 to 5490 eV, using the function NonlinearModelFit through a linear combination of the spectra of reference compounds.…”

Valence‐to‐core X‐ray emission spectroscopy of titanium compounds using energy dispersive detectors

“…[34][35][36] To date, most vtc-XES measurements have been performed at high-brightness user facilities, such as synchrotrons, while a few groups have developed laboratory-based systems. [37][38][39][40][41][42][43][44] A constant in all previous vtc-XES measurements is the use of wavelength dispersive detection techniques, where specially designed gratings or crystals are used to spatially separate the different photon energies in the emission spectrum. In earlier work, we have described a tabletop apparatus capable of performing static and dynamic XES measurements in the Kα and Kβ regions using a combination of a laser-based plasma source and energy-resolving cryogenic sensors.…”

Recent progress in the performance of HAPG based laboratory EXAFS and XANES spectrometers

“…One approach for novel XAS instrumentation employs spherically bent crystals in Rowland geometry. [2][3][4][5][6] These scanning type spectrometers offer spectral resolutions down to around 1 eV. Applications were, for example, reported in catalysis research, 7 environmental research 8 and in the investigation of actinides.…”