The heterodimer, XeAr, is a classic example of a weakly bound van der Waals molecule, which has a variety of accessible bound excited states that exhibit complex interactions. In this study, XeAr has been investigated in the 77,500–81,500 cm region using a combination of Resonance Enhanced Multi-Photon Ionization (REMPI) spectroscopy and Velocity Map Imaging (VMI). By monitoring REMPI and photodissociative product channels across the spectrum, several novel excited states, product channels, excited state symmetries and lifetimes, as well as highly localized perturbations were observed and characterized, including the first VMI study of Ar* dissociating from XeAr Rydberg states accessed by two-photon excitation. In this work we have analyzed 38 vibronic bands representing nine different electronic transitions, and we provide new assignments for two electronic transitions dissociating to the Xe* 5 [3/2] ( 80,323 cm) and Xe* 5 [7/2] ( 80,970 cm) limits. Several new predissociation product channels were identified at the two- and three-photon levels, including production of Xe* 5[5/2], Xe* 6[1/2], Xe* 6[1/2], Ar* 4[1/2], Ar* 4'[3/2], Ar* 4'[1/2], and Ar* 4[5/2]. Using the multidimensional analysis offered by VMI, we explore interesting photophysics whereby a resonant state that is reached after absorbing two photons can predissociate to yield Xe*, but which also can absorb a 3rd photon, yielding super-excited Ar*Xe that predissociates to Ar* limits. The ground state dissociation energy for XeAr was determined to be D = 114.4 ± 2.7 cm, in excellent agreement with previous measurements.

中文翻译：

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通过 XeAr 的里德堡态进行光解离动力学过程中的离子核心切换

异二聚体 XeAr 是弱结合范德华分子的典型例子，它具有多种可接近的束缚激发态，表现出复杂的相互作用。在这项研究中，结合共振增强多光子电离 (REMPI) 光谱和速度图成像 (VMI)，在 77,500–81,500 cm 区域对 XeAr 进行了研究。通过监测整个光谱范围内的 REMPI 和光解离产物通道，观察和表征了几种新颖的激发态、产物通道、激发态对称性和寿命，以及高度局域化的扰动，包括首次访问的 Ar* 从 XeAr Rydberg 态解离的 VMI 研究通过双光子激发。在这项工作中，我们分析了代表九种不同电子跃迁的 38 个电子振动带，并为解离到 Xe* 5 [3/2] ( 80,323 cm) 和 Xe* 5 [7/2] ( 80,970厘米）限制。在二光子和三光子水平上发现了几种新的预解离产物通道，包括 Xe* 5[5/2]、Xe* 6[1/2]、Xe* 6[1/2]、Ar* 4 的产生[1/2]、Ar* 4'[3/2]、Ar* 4'[1/2] 和 Ar* 4[5/2]。使用 VMI 提供的多维分析，我们探索有趣的光物理学，吸收两个光子后达到的共振态可以预解离产生 Xe*，但它也可以吸收第三个光子，产生超激发的 Ar*Xe，预解离为 Ar * 限制。 XeAr 的基态解离能确定为 D = 114.4 ± 2.7 cm，与之前的测量结果非常一致。