论文标题
分子中的核磁化分布效应：RA $^+$和RAF超细结构
Nuclear magnetization distribution effect in molecules: Ra$^+$ and RaF hyperfine structure
论文作者
论文摘要
最近，Ruiz \ textit {et al。} [自然\ textbf {581}，396（2020）]报告了放射性RAF分子的第一个激光光谱测量。这种和类似的分子被认为以寻找新的物理效应。辐射核很感兴趣，因为它是八杆核的，并且具有相反的平等水平。如果有可靠的理论预测，可以简化此类实验的准备。结果表明，对RAF分子的超细结构的准确预测需要考虑到镭核内部的有限磁化分布。对于原子，这种效果称为Bohr-Weisskopf（BW）效应。它的幅度取决于通常不知道的核磁化分布模型。我们表明，有可能以一个磁化分布分布参数来表达对超细结构常数的核磁化分布贡献：BW矩阵元素的相应氢样离子的$ 1S $ state。该参数可以从离子，原子或分子的精确实验和理论电子结构数据中提取，而无需明确处理任何核磁化分布模型。该方法可以应用于预测原子的超细结构和\ textit {Molecules}，并允许人们分离核和电子相关问题。它被用来计算有限的核磁化分布贡献$^{225} $ ra $^+$ cation和$^{225} $ RAF分子的超细结构。对于$^{225} $ RAF分子的基态，此贡献达到4 \％。
Recently the first laser spectroscopy measurement of the radioactive RaF molecule has been reported by Ruiz \textit{et al.} [Nature \textbf{581}, 396 (2020)]. This and similar molecules are considered to search for the New Physics effects. The radium nucleus is of interest as it is octupole-deformed and has close levels of opposite parity. The preparation of such experiments can be simplified if there are reliable theoretical predictions. It is shown that the accurate prediction of the hyperfine structure of the RaF molecule requires to take into account the finite magnetization distribution inside the radium nucleus. For atoms, this effect is known as the Bohr-Weisskopf (BW) effect. Its magnitude depends on the model of the nuclear magnetization distribution which is usually not well known. We show that it is possible to express the nuclear magnetization distribution contribution to the hyperfine structure constant in terms of one magnetization distribution dependent parameter: BW matrix element for $1s$-state of the corresponding hydrogen-like ion. This parameter can be extracted from the accurate experimental and theoretical electronic structure data for an ion, atom, or molecule without the explicit treatment of any nuclear magnetization distribution model. This approach can be applied to predict the hyperfine structure of atoms and \textit{molecules} and allows one to separate the nuclear and electronic correlation problems. It is employed to calculate the finite nuclear magnetization distribution contribution to the hyperfine structure of the $^{225}$Ra$^+$ cation and $^{225}$RaF molecule. For the ground state of the $^{225}$RaF molecule, this contribution achieves 4\%.
