Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
J Chem Phys. 2018 Jun 28;148(24):244304. doi: 10.1063/1.5030142.
We conducted a study of electronic structures and chemical bonding of gaseous ThO and ThO using velocity-map imaging and ab initio calculations. The electron affinity of neutral ThO molecule is reported for the first time with the value of 1.21(5) eV. We obtained a vibrationally resolved photoelectron spectroscopy of ThO and observed the symmetric stretching frequency of 824(40) cm for neutral molecules. One hot band transition is observed in the spectrum of ThO, which allows the measurement of symmetric stretching mode for ThO. The ground state of ThO is A with C symmetry: the detachment of an electron from the singly occupied molecular orbital (SOMO) results in the ground state of ThO. Kohn-Sham molecular orbital analyses reveal an σ and two weak π bonds for Th-O multiple bonds in ThO. Global minimum search methodology combined with quantum chemical calculations are used to find the minima of ThO and ThO, and the adiabatic detachment energy of ThO is calculated to be 3.26 eV at the coupled cluster with singles and doubles plus perturbative triples level. Our theoretical calculations suggest that the ground state of ThO is A' with a symmetry of C, while the most stable ThO is A with C symmetry; thus, the transition from ThO to ThO undergoes a significant geometry reorganization. Molecular orbital analyses suggest that the SOMO of ThO is mainly participated by O 2p and O to Th back donation was found in HOMO-2 molecular orbital. This investigation will shed some light on the understanding of covalent bonding in Th-contained molecules.
我们使用速度映射成像和从头算计算研究了气态 ThO 和 ThO 的电子结构和化学成键。首次报道了中性 ThO 分子的电子亲合势，其值为 1.21(5) eV。我们获得了 ThO 的振动分辨光电子能谱，并观察到中性分子的对称伸缩频率为 824(40) cm。在 ThO 的光谱中观察到一个热带跃迁，这允许测量 ThO 的对称伸缩模式。ThO 的基态为 A 对称性：从单占据分子轨道（SOMO）中脱离一个电子导致 ThO 的基态。Kohn-Sham 分子轨道分析表明，ThO 中的 Th-O 多重键具有 σ 和两个弱 π 键。全局最小搜索方法与量子化学计算相结合，用于寻找 ThO 和 ThO 的最小值，并计算 ThO 的绝热离解能为 3.26 eV，在耦合簇与单和双加微扰三的水平。我们的理论计算表明，ThO 的基态为 A'，具有 C 对称性，而最稳定的 ThO 为 A，具有 C 对称性；因此，从 ThO 到 ThO 的转变经历了显著的几何重排。分子轨道分析表明，ThO 的 SOMO 主要由 O 2p 参与，并且在 HOMO-2 分子轨道中发现了 O 到 Th 的反向捐赠。这项研究将有助于理解含 Th 分子中的共价键。
