Qian Chen-Hui, Zhu Guo-Zhu, Wang Lai-Sheng
Department of Chemistry , Brown University , Providence , Rhode Island 02912 , United States.
J Phys Chem Lett. 2019 Nov 7;10(21):6472-6477. doi: 10.1021/acs.jpclett.9b02679. Epub 2019 Oct 10.
We report photodetachment spectroscopy and high-resolution photoelectron imaging of -halogen substituted phenoxide anions, -XCHO (X = F, Cl, Br, I). The dipole moments of the -XCHO neutral radicals increase from 2.56 to 3.19 D for X = F to I, providing a series of similar molecules to allow the examination of charge-dipole interactions by minimizing molecule-dependent effects. Excited DBSs ([XCHO]) are observed for the four anions with binding energies of 8, 11, 24, and 53 cm, respectively, for X = F to I, below their respective detachment thresholds. The binding energies exhibit a linear correlation with the dipole moments of the neutral radicals, extrapolating to a critical dipole moment of 2.5 D for zero binding energy. Because of the small binding energy of the excited DBS of [FCHO], rotational autodetachment is observed to compete with vibrational autodetachment in the resonant photoelectron spectra, resulting in electrons with near zero kinetic energies.
我们报道了卤代苯氧负离子 -XCHO（X = F、Cl、Br、I）的光解离光谱和高分辨率光电子成像。对于X = F到I，-XCHO中性自由基的偶极矩从2.56 D增加到3.19 D，提供了一系列相似的分子，以便通过最小化分子相关效应来研究电荷 - 偶极相互作用。在低于各自解离阈值的情况下，观察到四种阴离子的激发双束缚态（[XCHO]*），其结合能分别为X = F到I时的8、11、24和53 cm⁻¹。结合能与中性自由基的偶极矩呈现线性相关性，外推至零结合能时的临界偶极矩为2.5 D。由于[FCHO]*激发双束缚态的结合能较小，在共振光电子能谱中观察到旋转自解离与振动自解离相互竞争，导致电子具有接近零的动能。
