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中国物理学会期刊

镱原子超精细诱导5d6s 3D1,3→6s2 1S0 E2跃迁及超精细常数的精确计算

CSTR: 32037.14.aps.73.20240028

Accurate calculation of hyperfine-induced 5d6s 3D1,3→6s2 1S0 E2 transitions and hyperfine constants of ytterbium atoms

CSTR: 32037.14.aps.73.20240028
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  • 在镱原子中, 利用 \rm 5d6s \; ^3D_1 \to 6s^2 \; ^1S_0 跃迁探索宇称破缺效应已经得到了深入的研究. 但是 \rm 5d6s\; ^3D_1 态与基态 \rm 6s^2 \; ^1S_0 之间的M1跃迁和超精细诱导E2跃迁很大程度上影响了宇称破缺信号的探测. 因此, 很有必要精确计算 \rm 5d6s\; ^3D_1 态与基态 \rm 6s^2\; ^1S_0 之间的M1跃迁和超精细诱导E2跃迁的跃迁概率. 本文利用多组态Dirac-Hartree-Fock理论精确计算了 \rm 5d6s \; ^3D_1 \to 6s^2 \; ^1S_0 M1跃迁和超精细诱导 \rm 5d6s \; ^3D_1,3 \to 6s^2 \; ^1S_0 E2跃迁的跃迁概率. 计算时详细分析了电子关联效应对跃迁概率的影响. 此外, 还分析了不同微扰态和不同超精细相互作用对跃迁概率的影响. 本文计算的 \rm ^3D_1,2,3 \rm ^1D_2 态的超精细常数与实验测量结果符合得很好, 从而证明了本文所用计算模型的合理性. 结合实验测量的超精细常数和本文理论计算所得的核外电子在原子核处的电场梯度, 重新评估了 ^173 Yb原子核电四极矩 Q = 2.89(5)\; \rm b , 评估结果与目前被推荐的结果符合得很好.

     

    The parity violation effects via the \mathrm5d6s\; ^3D_1 \to 6s^2 \; ^1S_0 transition have been extensively investigated in ytterbium atoms. However, the M1 transition between the excitation state \mathrm5d6s\; ^3D_1 and the ground state \mathrm6s^2 \; ^1S_0 , as well as the hyperfine-induced E2 transition, significantly affects the detection of parity violation signal. Therefore, it is imperative to obtain the accurate transition probabilities for the M1 and hyperfine-induced E2 transitions between the excitation state \mathrm 5d6s\; ^3D_1 and the ground state \mathrm6s^2\; ^1S_0 . In this work, we use the multi-configuration Dirac-Hartree-Fock theory to precisely calculate the transition probabilities for the \mathrm 5d6s \; ^3D_1 \to 6s^2 \; ^1S_0 M1 and hyperfine-induced \mathrm 5d6s \; ^3D_1,3 \to 6s^2 \; ^1S_0 E2 transitions. We extensively analyze the influences of electronic correlation effects on the transition probabilities according to our calculations. Furthermore, we analyze the influences of different perturbing states and various hyperfine interactions on the transition probabilities. The calculated hyperfine constants of the e \mathrm^3D_1,2,3 and \mathrm ^1D_2 states accord well with experimental measurements, validating the rationality of our computational model. By combining experimentally measured hyperfine constants with the theoretically derived electric field gradient of the extra nuclear electrons at the nucleus, we reevaluate the nuclear quadrupole moment of the ^173 Yb nucleus as Q = 2. 89(5) \;\rm b , showing that our result is in excellent agreement with the presently recommended value.

     

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