Spherically bent crystal analyzers (SBCAs) are the dominant high-resolution hard X-ray optic in the ongoing rebirth of laboratory-based X-ray absorption fine structure (XAFS) and X-ray emission spectroscopy (XES) as well as in synchrotron methods such as high energy resolution fluorescence detection (HERFD) and non-resonant X-ray Raman scattering (XRS). In the overwhelming majority of cases, SBCAs are implemented in a ‘symmetric’ configuration on the Rowland circle, wherein the diffracting crystal plane is nominally coincident with the analyzer surface. We report here comprehensive investigations of ‘asymmetric’ operation of SBCA on the Rowland circle, wherein the diffracting crystal plane is not coincident with the optical surface of the analyzer. First, we have developed a laboratory spectrometer for XAFS and XES that is specialized for asymmetric SBCA operation. Here we find several benefits, including the capacity to use a single SBCA over a very wide energy range via ‘hkl hopping’ and the frequent ability to eliminate Johann error, the most prevalent energy-broadening mechanism when using SBCA symmetrically on the Rowland circle. Second, we expand these ideas to synchrotron facilities with a demonstration study of HERFD and XRS where asymmetric operation also provided advantage. Our results suggest that large-array systems for HERFD augmented with an additional mechanical degree of freedom could streamline user operation and also indicate benefits to XRS in the asymmetric configuration, where larger solid angle, larger sample-to-detector distance, and decreased Johann error can be achieved simultaneously.
Gironda, Anthony J., et al. "Asymmetric Rowland circle geometries for spherically bent crystal analyzers in laboratory and synchrotron applications." Journal of Analytical Atomic Spectrometry, vol. 39, no. 5, Mar. 2024. https://doi.org/10.1039/d3ja00437f
Gironda, Anthony J., Abramson, Jared E., Chen, Yeu, Solovyev, Mikhail, Sterbinsky, George E., & Seidler, Gerald T. (2024). Asymmetric Rowland circle geometries for spherically bent crystal analyzers in laboratory and synchrotron applications. Journal of Analytical Atomic Spectrometry, 39(5). https://doi.org/10.1039/d3ja00437f
Gironda, Anthony J., Abramson, Jared E., Chen, Yeu, et al., "Asymmetric Rowland circle geometries for spherically bent crystal analyzers in laboratory and synchrotron applications," Journal of Analytical Atomic Spectrometry 39, no. 5 (2024), https://doi.org/10.1039/d3ja00437f
@article{osti_2569672,
author = {Gironda, Anthony J. and Abramson, Jared E. and Chen, Yeu and Solovyev, Mikhail and Sterbinsky, George E. and Seidler, Gerald T.},
title = {Asymmetric Rowland circle geometries for spherically bent crystal analyzers in laboratory and synchrotron applications},
annote = {Spherically bent crystal analyzers (SBCAs) are the dominant high-resolution hard X-ray optic in the ongoing rebirth of laboratory-based X-ray absorption fine structure (XAFS) and X-ray emission spectroscopy (XES) as well as in synchrotron methods such as high energy resolution fluorescence detection (HERFD) and non-resonant X-ray Raman scattering (XRS). In the overwhelming majority of cases, SBCAs are implemented in a ‘symmetric’ configuration on the Rowland circle, wherein the diffracting crystal plane is nominally coincident with the analyzer surface. We report here comprehensive investigations of ‘asymmetric’ operation of SBCA on the Rowland circle, wherein the diffracting crystal plane is not coincident with the optical surface of the analyzer. First, we have developed a laboratory spectrometer for XAFS and XES that is specialized for asymmetric SBCA operation. Here we find several benefits, including the capacity to use a single SBCA over a very wide energy range via ‘hkl hopping’ and the frequent ability to eliminate Johann error, the most prevalent energy-broadening mechanism when using SBCA symmetrically on the Rowland circle. Second, we expand these ideas to synchrotron facilities with a demonstration study of HERFD and XRS where asymmetric operation also provided advantage. Our results suggest that large-array systems for HERFD augmented with an additional mechanical degree of freedom could streamline user operation and also indicate benefits to XRS in the asymmetric configuration, where larger solid angle, larger sample-to-detector distance, and decreased Johann error can be achieved simultaneously.},
doi = {10.1039/d3ja00437f},
url = {https://www.osti.gov/biblio/2569672},
journal = {Journal of Analytical Atomic Spectrometry},
issn = {ISSN 1364-5544},
number = {5},
volume = {39},
place = {United States},
publisher = {Royal Society of Chemistry},
year = {2024},
month = {03}}
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 269, Issue 3https://doi.org/10.1016/0168-9002(88)90145-3
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