In a combined experimental and theoretical study we investigate the $7dnl$ and $8pnl$ ($n\ge 11, l=9–12$) doubly excited planetary states of Sr. The experimental spectrum was obtained using a five-photon resonant excitation scheme. The method of configuration interaction with exterior complex scaling was used to compute the energy-level structure and dynamics of the two highly excited electrons from first principles. Good quantitative agreement was obtained with the spectra we recorded, and the theoretical calculations shed light on their complex structure and the signatures of electron correlations therein. The two-electron probability densities we calculated reveal the strongly correlated angular motion of the two electrons in the $7dnl$ and $8pnl$ planetary states, and confirm quantitatively the predictions of the frozen-planet approximation describing electron dynamics as the polarization of the fast inner electron by the electric field of the outer “frozen” electron.

中文翻译：

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Sr+7d和8p阈值以下Sr行星态的结构和电子动力学

在结合实验和理论研究中，我们调查了 $7dn升$ 和 $8磷n升$ ($n\ge 11, 升=9——12$) Sr 的双激发行星态。实验光谱是使用五光子共振激发方案获得的。使用外部复杂标度的构型相互作用方法从第一原理计算两个高度激发的电子的能级结构和动力学。我们记录的光谱获得了良好的定量一致性，理论计算阐明了它们的复杂结构和其中电子相关性的特征。我们计算的两电子概率密度揭示了两个电子在$7dn升$ 和 $8磷n升$ 行星状态，并定量确认冻结行星近似的预测，将电子动力学描述为外部“冻结”电子的电场对快速内部电子的极化。