Anion photoelectron spectroscopy and chemical bonding of ThO2- and ThO3

Yanli Li; Jinghan Zou; Xiao-Gen Xiong; Hua Xie; Zichao Tang; Min Ge; Yafan Zhao; Hongtao Liu

doi:10.1063/1.5030142

Anion photoelectron spectroscopy and chemical bonding of ThO₂^- and ThO₃

J Chem Phys. 2018 Jun 28;148(24):244304. doi: 10.1063/1.5030142.

Authors

Yanli Li¹, Jinghan Zou², Xiao-Gen Xiong¹, Hua Xie³, Zichao Tang⁴, Min Ge¹, Yafan Zhao⁵, Hongtao Liu¹

Affiliations

¹ Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
⁴ State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
⁵ Institute of Applied Physics and Computational Mathematics, Beijing 10088, China.

PMID: 29960323
DOI: 10.1063/1.5030142

Abstract

We conducted a study of electronic structures and chemical bonding of gaseous ThO₂^- and ThO₃^- using velocity-map imaging and ab initio calculations. The electron affinity of neutral ThO₂ molecule is reported for the first time with the value of 1.21(5) eV. We obtained a vibrationally resolved photoelectron spectroscopy of ThO₂^- and observed the symmetric stretching frequency of 824(40) cm^-1 for neutral molecules. One hot band transition is observed in the spectrum of ThO₂^-, which allows the measurement of symmetric stretching mode for ThO₂^-. The ground state of ThO₂^- is ²A₁ with C_2v symmetry: the detachment of an electron from the singly occupied molecular orbital (SOMO) results in the ground state of ThO₂. Kohn-Sham molecular orbital analyses reveal an σ and two weak π bonds for Th-O multiple bonds in ThO₂. Global minimum search methodology combined with quantum chemical calculations are used to find the minima of ThO₃ and ThO₃^-, and the adiabatic detachment energy of ThO₃^- 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 ThO₃ is ¹A' with a symmetry of C_s, while the most stable ThO₃^- is ²A₁ with C_2v symmetry; thus, the transition from ThO₃^- to ThO₃ undergoes a significant geometry reorganization. Molecular orbital analyses suggest that the SOMO of ThO₃^- 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.