Characterization of the thorium-229 defect structure in CaF<sub>2</sub> crystals
Abstract Recent advancements in laser excitation of the low-energy thorium-229 ( 229 Th) nuclear isomeric state in calcium fluoride (CaF 2 ) single crystals render this system a promising candidate for a solid-state nuclear clock. Nonetheless, the precise experimental determination of the microscopic ion configuration surrounding the doped 229 Th and its electronic charge state remains a critical challenge. Such characterization is essential for precisely controlling the clock transition and evaluating the performance of this solid-state nuclear clock system. In this study, we use x-ray absorption fine structure spectroscopy of 229 Th:CaF 2 to investigate the charge state and coordination environment of doped 229 Th. The results indicate that 229 Th displays a 4+ oxidation state at the substitutional site of a Ca 2+ ion, with charge compensated provided by two F − ions positioned at interstitial sites adjacent to 229 Th.
Authors
- Thorsten Schumm (ORCID: https://orcid.org/0000-0002-1066-202X)
- Tetsuo Honma (ORCID: https://orcid.org/0000-0001-6617-3543)
- Martin Pimon (ORCID: https://orcid.org/0000-0001-7784-463X)
- Kiyofumi Nitta
- Fabian Schaden (ORCID: https://orcid.org/0000-0001-7154-0440)
- Rei Yamamoto
- Michael Bartokos (ORCID: https://orcid.org/0009-0004-7610-9122)
- Oki Sekizawa
- Sayuri Takatori
- Takahiko Masuda (ORCID: https://orcid.org/0000-0001-8122-5145)
- Stephan Pollitt (ORCID: https://orcid.org/0000-0002-6589-0134)
- Takumi Yomogida (ORCID: https://orcid.org/0000-0002-2005-0027)
- Tomáš Šikorský (ORCID: https://orcid.org/0000-0003-0280-0928)
- Niyusha Hosseini
- Kjeld Beeks (ORCID: https://orcid.org/0000-0002-8707-6723)
- A. Yoshimi (ORCID: https://orcid.org/0000-0002-2438-1384)
- A. Leitner (ORCID: https://orcid.org/0009-0007-1156-1881)
- T. Hiraki (ORCID: https://orcid.org/0000-0002-6235-5830)
- L. Toscani De Col (ORCID: https://orcid.org/0009-0001-1907-0688)
- I. Morawetz (ORCID: https://orcid.org/0009-0001-4071-7749)
- Yoshio Takahashi (ORCID: https://orcid.org/0000-0001-7860-2341)
- K. Yoshimura (ORCID: https://orcid.org/0000-0002-2415-718X)
- Andreas Grüneis (ORCID: https://orcid.org/0000-0002-4984-7785)
- Koichi Okai
- Thomas Riebner
Institutions
- Japan Atomic Energy Agency (JP)
- Okayama University of Science (JP)
- TU Wien (AT)
- Okayama University (JP)
- Hochschule Campus Wien (AT)
- Japan Synchrotron Radiation Research Institute (JP)
- École Polytechnique Fédérale de Lausanne (CH)
- The University of Tokyo (JP)
Publication Details
- Journal
- New Journal of Physics
- Published
- 2025-04-01
- DOI
- https://doi.org/10.1088/1367-2630/adce22
- Citations
- 1
- Primary Topic
- Nuclear Materials and Properties
- Type
- article
- Field-Weighted Citation Impact
- 0.52
Funders
- Austrian Science Fund
- Japan Society for the Promotion of Science
- H2020 European Research Council