Photoionization of an atom in the presence of a neighboring atom of different species is studied. The latter first undergoes resonant photoexcitation, leading to an autoionizing state of the diatomic system. Afterwards, the excitation energy is transferred radiationlessly via a two-center Auger process to the other atom, causing its ionization. Assuming a fixed internuclear distance, it has been predicted theoretically that this indirect ionization pathway can strongly dominate over the direct photoionization. Here, we extend the theory of resonant two-center photoionization by including the nuclear motion in van-der-Waals molecules. An analytical formula is derived reflecting the influence of molecular vibrational dynamics on the relative strength of the two-center channel. For the specific example of Li-He dimers we show that the two-center autoionizing resonances are split by the nuclear motion into multiplets, with the resonance lines reaching a comparable level of enhancement over direct photoionization as is obtained in a model based on spatially fixed nuclei.

中文翻译：

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核运动对共振两中心光电离的影响

研究了在不同物种的相邻原子存在下原子的光电离。后者首先经历共振光激发，导致双原子系统的自电离状态。之后，激发能通过两中心俄歇过程无辐射地转移到另一个原子，从而使其电离。假设核之间的距离固定，则理论上已经预测，这种间接电离途径可以在直接光电离中占据主导地位。在这里，我们通过将核运动包括在范德华分子中来扩展共振两中心光电离的理论。推导了一个解析公式，该公式反映了分子振动动力学对两中心通道相对强度的影响。