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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Photoelectron Spectroscopy and ab Initio Study of B_3~- and B_4~- anions and Their Neutrals
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Photoelectron Spectroscopy and ab Initio Study of B_3~- and B_4~- anions and Their Neutrals

机译：B_3〜-和B_4〜-阴离子及其中性的光电子能谱和从头算研究

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The two smallest boron clusters (B_3 and B_4) in their neutral and anionic forms were studied by photoelectron spectroscopy and ab initio calculations. Vibrationally resolved photoelectron spectra were observed for B_3~- at three photon energies (355, 266, and 193 nm), and the electron affinity of B_3 was measured to be 2.82 ± 0.02 eV. An unusually intense peak due to two-electron transitions was observed in the 193-nm spectrum of B_3~- at 4.55 eV and its origin was theoretically characterized. We confirmed that both B_3~- and B_3 are π and σ aromatic systems with D_(3h) symmetry. The photoelectron spectra of B_4~- were also obtained at the three photon energies, but much broader spectra were observed. The B_4~- anion was found to have the lowest electron detachment energy (～1.6 eV) among all boron clusters with three or more atmos, consistent with its extremely weak mass signals. The neutral B_4 cluster was found to have a D_(2h) rhombus structure, which is only slightly distorted from a perfect square. For B_4~-, we identified computationally two low-lying isomers (~2B_(lu) and ~2A_g) both with D_(2h) symmetry, with the ~2B_(lu) state slightly more stable, which is confirmed through comparison of the calculated spectra with the experimental spectra. The chemical bonding of the two small boron clusters is discussed in terms of aromaticity and antiaromaticity both in the π and σ framework. We demonstrated that the aromaticity and antiaromaticity concepts provide us a clear explanation of the chemical structure and bonding in these two boron clusters.
机译：通过光电子能谱和从头算计算研究了两个最小的中性和阴离子形式的硼簇（B_3和B_4）。在三个光子能量（355、266和193 nm）下观察到B_3〜-的振动分辨光电子能谱，测得B_3的电子亲和力为2.82±0.02 eV。在B_3〜-的193 nm光谱中，在4.55 eV处观察到一个由两个电子跃迁引起的异常强烈的峰，并从理论上对其起源进行了表征。我们确认B_3〜-和B_3都是具有D_（3h）对称性的π和σ芳族体系。在三种光子能量下也获得了B_4-的光电子能谱，但观察到的光谱要宽得多。发现在具有三个或更多原子序数的所有硼簇中，B_4〜-阴离子具有最低的电子脱离能（〜1.6 eV），这与其极弱的质量信号一致。发现中性B_4团簇具有D_（2h）菱形结构，该结构仅与理想正方形略有扭曲。对于B_4〜-，我们通过计算确定了两个低等位异构体（〜2B_（lu）和〜2A_g），它们都具有D_（2h）对称性，〜2B_（lu）状态稍微更稳定，这可以通过比较计算光谱与实验光谱。讨论了两个小的硼团簇的化学键合，分别在π和σ构架上具有芳香性和抗芳香性。我们证明了芳香性和抗芳香性概念为我们提供了对这两个硼簇中化学结构和键合的清晰解释。

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