Scattering of a Rydberg electron by ground-state atoms (scatterers) located in its classically forbidden region can be viewed as electron-atom scattering with negative incident energy. We propose a treatment of this unusual case of scattering in the context of long-range molecular potentials arising from the interaction of a Rydberg electron with ground state atoms. We describe a treatment leading to proper equivalents of scattering lengths and phase shifts for negative incident energies, which becomes advantageous when a Rydberg atom is penetrated by more than one scatterer and the Rydberg electron scatters back and forth between the atoms in the classically allowed and forbidden regions. We apply this approach to Cs and Rb samples, and find evidence for a resonance-like feature for their 3 S 1 states.

中文翻译：

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负动能禁区的里德堡电子-原子散射

里德堡电子被位于其经典禁区的基态原子（散射体）散射的过程可被视为具有负入射能量的电子原子散射。我们提出一种在Rydberg电子与基态原子相互作用产生的远距离分子势的情况下处理这种不寻常的散射情况的方法。我们描述了一种导致负入射能量的散射长度和相移适当当量的处理，当Rydberg原子被多个散射体穿透并且Rydberg电子在经典允许和禁止的原子之间来回散射时，这将变得非常有利地区。我们将这种方法应用于Cs和Rb样本，并找到3 S 1状态具有类似共振特征的证据。