Zhang Yue-Rou, Yuan Dao-Fu, Wang Lai-Sheng
Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.
J Phys Chem Lett. 2022 Mar 10;13(9):2124-2129. doi: 10.1021/acs.jpclett.2c00275. Epub 2022 Feb 28.
Polar molecules can bind an electron in a diffuse orbital due to the charge-dipole interaction. Electronic excited states of polar molecules can also bind an electron to form core-excited dipole-bound states (DBSs), analogous to core-excited Rydberg states. However, core-excited DBSs have not been observed because of the complicated electronic structure of molecular systems. Here, we report the observation of a core-excited DBS in the pyrazolide anion as a result of the favorable electronic structure of the neutral pyrazolyl core, which has a low-lying excited state (ÃB) only 266 cm above its ground state (X̃A). The binding energy of the DBS associated with the ground state is measured to be 221 cm, while that of the core-excited DBS is 276 cm, which is still a bound state relative to the detachment threshold. Vibrational Feshbach resonances are observed for both DBSs, and their autodetachment behaviors are studied by resonant photoelectron imaging.
极性分子可由于电荷 - 偶极相互作用在弥散轨道中束缚一个电子。极性分子的电子激发态也能束缚一个电子以形成芯激发偶极束缚态（DBSs），类似于芯激发里德堡态。然而，由于分子体系复杂的电子结构，芯激发DBSs尚未被观测到。在此，我们报告了在吡唑阴离子中观测到芯激发DBSs，这是由于中性吡唑基核具有有利的电子结构，其低激发态（ÃB）仅比基态（X̃A）高266厘米。与基态相关的DBSs的束缚能测量为221厘米，而芯激发DBSs的束缚能为276厘米，相对于脱离阈值而言它仍是一个束缚态。两种DBSs均观测到了振动费什巴赫共振，并通过共振光电子成像研究了它们的自脱离行为。
