AI 中文总结
该研究针对²²⁹Th核同质异能素光谱学所需的Th³⁺低激发态，采用相对论耦合簇等方法计算了超精细常数、同位素位移等，预测了7s态同质异能素位移，为核钟开发提供基准原子数据。
AI 中文摘要
针对与²²⁹Th核同质异能素光谱学相关的Th³⁺低激发态，我们开展了超精细常数、同位素位移及同质异能素位移的高精度计算。采用包含单、双、三重激发的相对论耦合簇方法计算了移除能和超精细常数，证明了高阶关联效应的重要性；同时使用CI+MBPT和CI+全阶两种方法评估了5f₅/2-7s跃迁的同位素位移，给出了理论不确定度的估计值。研究发现该同位素位移主要由场位移主导，质量位移贡献可忽略不计。结合计算得到的场位移系数与基态和同质异能态的核均方电荷半径差的测量值，我们预测7s态的同质异能素位移为ΔE^(m,g)=0.9(1) GHz。这些结果为Th³⁺提供了基准原子数据，支持²²⁹Th的持续精密光谱学研究及核钟的开发。
英文摘要
We present high-precision calculations of the hyperfine constants, isotope shift, and isomer shift in low-lying states of Th3+ relevant to spectroscopy of the 229Th nuclear isomer. The removal energy and hyperfine constants are calculated using a relativistic coupled-cluster method including single, double, and triple excitations, demonstrating the importance of higher-order correlation effects. The isotope shift of the 5f_5/2 -7s transition is evaluated using both the CI+MBPT and CI+all-order methods, providing an estimate of the theoretical uncertainty. We find that the isotope shift is dominated by the field shift, with the mass shift contributing negligibly. Combining the calculated field-shift coefficient with the measured difference in the nuclear mean-square charge radii of the ground and isomeric states, we predict the 7s isomer shift to be (Delta E^(m,g))= 0.9(1) GHz. These results provide benchmark atomic data for Th3+ and support ongoing precision spectroscopy of 229Th and the development of a nuclear clock.
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