Laser Mössbauer spectroscopy of 229 Th in CaF 2

Mössbauer spectroscopy is widely used in chemistry, geology, and solid-state physics to probe the local physical and chemical environment of nuclei in materials. Here, we extended this technique into the optical range using a vacuum ultraviolet laser to probe the low-energy nuclear transitions of thorium-229 ( 229 Th) doped in calcium fluoride (CaF 2 ) crystals. We discovered four distinct doping sites for the thorium ions, determined the characteristic electric field gradients emerging from the interaction with the host crystal, and identified the microscopic structure of the two dominant configurations. Site-selective laser excitation enabled the study of the isomeric state lifetime and laser-induced quenching for all sites. This technique provides a powerful probe of the nuclear environment, yielding foundational data for designing future solid-state nuclear clocks.

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Publication Details

Journal
Science
Published
2026-08-20
DOI
https://doi.org/10.1126/science.aea7978
Primary Topic
Advanced Frequency and Time Standards
Type
article
Field-Weighted Citation Impact
0.00

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article

Laser Mössbauer spectroscopy of 229 Th in CaF 2

Thorsten Schumm, Georgy A. Kazakov, Martin Pimon, Fabian Schaden et al.
Science
Advanced Frequency and Time Standards
article

Laser Mössbauer spectroscopy of 229 Th in CaF 2

Thorsten Schumm, Georgy A. Kazakov, Martin Pimon, Fabian Schaden, Michael Bartokos, Sayuri Takatori, Martin Pressler, Takahiko Masuda, Thomas Pronebner, Thomas LaGrange, Tomáš Šikorský, N. Sasao, Kjeld Beeks, A. Yoshimi, A. Leitner, T. Hiraki, Ryoichiro Ogake, L. Toscani De Col, I. Morawetz, K. Yoshimura, Kotaro Shimizu, Ming Guan, F. Schneider, Andreas Grüneis, Yuta Fukunaga, Koichi Okai
article en

Abstract

Mössbauer spectroscopy is widely used in chemistry, geology, and solid-state physics to probe the local physical and chemical environment of nuclei in materials. Here, we extended this technique into the optical range using a vacuum ultraviolet laser to probe the low-energy nuclear transitions of thorium-229 ( 229 Th) doped in calcium fluoride (CaF 2 ) crystals. We discovered four distinct doping sites for the thorium ions, determined the characteristic electric field gradients emerging from the interaction with the host crystal, and identified the microscopic structure of the two dominant configurations. Site-selective laser excitation enabled the study of the isomeric state lifetime and laser-induced quenching for all sites. This technique provides a powerful probe of the nuclear environment, yielding foundational data for designing future solid-state nuclear clocks.

ScienceVol. 393(6813)
Okayama University of Science (JP), TU Wien (AT), Charles University (CZ), Hochschule Campus Wien (AT), Wolfgang Pauli Institute (AT), École Polytechnique Fédérale de Lausanne (CH)
European Partnership on Metrology, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Austrian Science Fund, Japan Society for the Promotion of Science, Japan Science and Technology Agency, HORIZON EUROPE European Research Council
Life in Land
Openalex Percentile: Top 12%
Advanced Frequency and Time Standards
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