Zhang Yue-Rou, Yuan Dao-Fu, Wang Lai-Sheng
Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.
Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
J Phys Chem Lett. 2023 Aug 24;14(33):7368-7381. doi: 10.1021/acs.jpclett.3c01994. Epub 2023 Aug 11.
Molecular anions with polar neutral cores can support highly diffuse dipole-bound states below their detachment thresholds due to the long-range charge-dipole interaction. Such nonvalence states constitute a special class of excited electronic states for anions and were observed in early photodetachment experiments to measure the electron affinities of organic radicals. Recent experimental advances, in particular, the ability to create cold anions using a cryogenically cooled Paul trap, have allowed the investigation of dipole-bound excited states at a new level. For the first time, the zero-point level of dipole-bound excited states can be observed via resonant two-photon detachment, and resonant photoelectron spectroscopy can be performed via the above-threshold vibrational levels (Feshbach resonances) of the dipole-bound states. This Perspective describes recent progress in the investigation of dipole-bound states in the authors' lab using an electrospray photoelectron spectroscopy apparatus equipped with a cryogenically cooled Paul trap and high-resolution photoelectron imaging.
由于长程电荷-偶极相互作用，具有极性中性核的分子阴离子可以在其脱离阈值以下支持高度弥散的偶极束缚态。这类非价态构成了阴离子激发电子态的一个特殊类别，并且在早期用于测量有机自由基电子亲和能的光电子脱离实验中被观测到。近期的实验进展，特别是利用低温冷却的保罗阱产生冷阴离子的能力，使得偶极束缚激发态的研究达到了一个新水平。首次能够通过共振双光子脱离观测偶极束缚激发态的零点能级，并且可以通过偶极束缚态的阈上振动能级（费什巴赫共振）进行共振光电子能谱分析。本综述介绍了作者实验室使用配备低温冷却保罗阱和高分辨率光电子成像的电喷雾光电子能谱仪在偶极束缚态研究方面的最新进展。
