Energy splitting and isomer shift of <sup>229</sup>Th in VUV-transparent crystals
Energy splitting and isomer shift of <sup>229</sup>Th in VUV-transparent crystals
Lan, Dr. Haoyang 1Zhang, Mr. Tianyi Chen, Mr. Zhongyi 2Wu, Dr. Di 1wang, Dr. meizhi 1Ma, Dr. Boyao Yan, Prof. Xueqing 颜学庆3
作者信息
- 1. Peking University
- 2. University of Science and Technology Beijing
- 3. Peking University Faculty of Sciences
- 折叠
摘要
The 229Th isomeric transition around 8.4 eV offers a route to solid-state nuclear clocks, but its frequency is modified by the isomer shift and by the electric quadrupole interaction in the host crystal. We report a first-principles study of seven Th defect sites in four VUV-transparent hosts: ThF4, Th:CaF2, Th:SrF2 and Th:LiF. Calculations are performed with PBE, R2SCAN and HSE06 functionals, yielding the Th 5f/6d/7s/7p valence weights, isomer shifts, EFG tensors (Vzz,η) and the complete I = 5/2 and I = 3/2 quadrupole level structures. The EFG and quadrupole splittings are insensitive to the functional (at most 3.8%), whereas the isomer shift varies by 25–46 MHz and tracks the Th Nl weight. The defect configuration controls the EFG: F-90 and F-180 centres have opposite Vzz signs and differ in magnitude by up to a factor of 2.5; ground-state splittings span 48/96 MHz in Th:LiF to 429/858 MHz in CaF2 F-180, with isomer-state splittings of 91–816 MHz. The method is validated against the published ThF4 shift decomposition (0.6–1.4 MHz), an independent calculation of its level structure (0.7–1.1% in Vzz and ≤ 8 MHz in the splittings), and TDHF/RPA field-shift coefficients (0.2–1.8%). These results provide a functional- and configuration-resolved database for interpreting host-dependent 229Th clock frequencies, and identify quadrupole splitting as the more transferable electronic observable.
Abstract
The 229Th isomeric transition around 8.4 eV offers a route to solid-state nuclear clocks, but its frequency is modified by the isomer shift and by the electric quadrupole interaction in the host crystal. We report a first-principles study of seven Th defect sites in four VUV-transparent hosts: ThF4, Th:CaF2, Th:SrF2 and Th:LiF. Calculations are performed with PBE, R2SCAN and HSE06 functionals, yielding the Th 5f/6d/7s/7p valence weights, isomer shifts, EFG tensors (Vzz,) and the complete I = 5/2 and I = 3/2 quadrupole level structures. The EFG and quadrupole splittings are insensitive to the functional (at most 3.8%), whereas the isomer shift varies by 2546 MHz and tracks the Th Nl weight. The defect configuration controls the EFG: F-90 and F-180 centres have opposite Vzz signs and differ in magnitude by up to a factor of 2.5; ground-state splittings span 48/96 MHz in Th:LiF to 429/858 MHz in CaF2 F-180, with isomer-state splittings of 91816 MHz. The method is validated against the published ThF4 shift decomposition (0.61.4 MHz), an independent calculation of its level structure (0.71.1% in Vzz and 8 MHz in the splittings), and TDHF/RPA field-shift coefficients (0.21.8%). These results provide a functional- and configuration-resolved database for interpreting host-dependent 229Th clock frequencies, and identify quadrupole splitting as the more transferable electronic observable.关键词
solid-state nuclear clock/energy splitting/isomer shift引用本文复制引用
Lan, Dr. Haoyang,Zhang, Mr. Tianyi,Chen, Mr. Zhongyi,Wu, Dr. Di,wang, Dr. meizhi,Ma, Dr. Boyao,Yan, Prof. Xueqing 颜学庆.Energy splitting and isomer shift of <sup>229</sup>Th in VUV-transparent crystals[EB/OL].(2026-11-01)[2026-11-04].https://chinaxiv.org/abs/202611.00026.学科分类
原子能技术基础理论
