Implementation of cryogenic tender X-ray HR-XANES spectroscopy at the ACT station of the CAT-ACT beamline at the KIT Light Source

Abstract

The ACT experimental station of the CAT-ACT wiggler beamline at the Karlsruhe Institute of Technology (KIT) Light Source is dedicated to the investigation of radionuclide materials with radioactivities up to 1000000 times the exemption limit by various speciation techniques applying monochromatic X-rays. In this article, the latest technological developments at the ACT station that enable high-resolution X-ray absorption near-edge structure (HR-XANES) spectroscopy for low radionuclide loading samples are highlighted – encompassing the investigation of actinide elements down to 1 p.p.m. concentration – combined with a cryogenic sample environment reducing beam-induced sample alterations. One important part of this development is a versatile gas tight plexiglass encasement ensuring that all beam paths in the five-analyzer-crystal Johann-type X-ray emission spectrometer run within He atmosphere. The setup enables the easy exchange between different experiments (conventional X-ray absorption fine structure, HR-XANES, high-energy or wide-angle X-ray scattering, tender to hard X-ray spectroscopy) and opens up the possibility for the investigation of environmental samples, such as specimens containing transuranium elements from contaminated land sites or samples from sorption and diffusion experiments to mimic the far field of a breached nuclear waste repository.

Synchrotron Radiation Techniques and their Application to Actinide Materials

“…Synchrotron Radiation Laboratory (SSRL), Menlo Park, California; MARS (Solari et al, 2009) at SOLEIL, Gifsur-Yvette, France; CAT-ACT (Dardenne et al, 2009;Rothe et al, 2012;Schacherl et al, 2022b;Zimina et al, 2017) at the Karlsruhe Research Accelerator (KARA, former ANKA) in Karlsruhe, Germany; MicroXAS (Borca et al, 2009) at the Swiss Light Source (SLS), Villigen, Switzerland; and ROBL-II (Kvashnina and Scheinost, 2016;Scheinost et al, 2021) at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. Generally, dedicated beamlines have several experimental stations.…”

Np(V) Retention at the Illite du Puy Surface

“…The sample at pH 9 was studied after t c = 11 days and after t c = 811 days. A clear improvement in signal-to-noise ratio despite shorter acquisition time is visible (Figure ), which was achieved due to improvements in the experimental setup at the beamline. , Nevertheless, the spectral features remained the same, an indication that no significant changes in the Np­(IV)/Np­(V) ratio on the IdP A at pH 9 occurred even after longer contact times.…”

“…Np L 3 -edge extended X-ray absorption fine structure (EXAFS) probes type, number, interatomic distances of atoms neighboring Np, and local structural disorder . Recently, high-energy resolution X-ray absorption near-edge structure (HR-XANES) spectroscopy − at the Np M 5 -edge was shown to be a valuable tool for oxidation state studies on Np loadings down to 1 ppm. − In addition, the Np M 5 -edge HR-XANES spectra are very sensitive to changes of the Np bonding properties. , …”

Synthesis, Characterization, and Stability of Two Americium Vanadates, AmVO3 and AmVO4

“…Additionally, Am L 3 edge and V K-edge XANES measurements were performed at the INE-Beamline 18 of the KIT Light Source, Karlsruhe, Germany. The radiation protection measures were kept identical to those used at the ACT station.…”