Zhu Guo-Zhu, Cheung Ling Fung, Liu Yuan, Qian Chen-Hui, Wang Lai-Sheng
Department of Chemistry , Brown University , Providence , Rhode Island 02912 , United States.
J Phys Chem Lett. 2019 Aug 1;10(15):4339-4344. doi: 10.1021/acs.jpclett.9b01743. Epub 2019 Jul 19.
We report the observation of a dipole-bound state (DBS) 659 cm below the electron detachment threshold of cryogenically cooled deprotonated 4,4'-biphenol anion (bPh) and 19 of its lowest vibrational levels. Resonant two-photon photoelectron imaging (R2P-PEI) via the vibrational levels of the DBS displays a sharp peak with a constant binding energy. This observation indicates vertical detachment from the vibrational levels of the DBS to the corresponding neutral levels with the conservation of the vibrational energy, suggesting that the highly diffuse electron in the DBS has little effect on the neutral core. The R2P-PEI spectra also exhibit two features at lower binding energies, which come from intersystem crossings from the DBS to two lower-lying valence-bound triplet excited states of bPh. The current study discloses the first R2P-PEI spectra from vibrational excited states of a DBS and direct spectroscopic evidence of transitions from a DBS to valence-bound states of anions.
我们报告了在低温冷却的去质子化4,4'-联苯酚阴离子（bPh）的电子脱离阈值以下659厘米处观察到一个偶极束缚态（DBS）及其19个最低振动能级。通过DBS的振动能级进行的共振双光子光电子成像（R2P-PEI）显示出一个具有恒定结合能的尖锐峰。这一观察结果表明，从DBS的振动能级到相应的中性能级的垂直脱离伴随着振动能量的守恒，这表明DBS中高度弥散的电子对中性核几乎没有影响。R2P-PEI光谱在较低结合能处还表现出两个特征，这来自于从DBS到bPh的两个较低的价态束缚三重激发态的系间窜越。当前的研究揭示了来自DBS振动激发态的首个R2P-PEI光谱以及从DBS到阴离子价态束缚态跃迁的直接光谱证据。
