title: Photoelectron spectroscopy and theoretical studies of gaseous uranium hexachlorides in different oxidation states: UCl6 (q-) (q = 0-2).
abstract: Uranium chlorides are important in actinide chemistry and nuclear industries, but their chemical bonding and many physical and chemical properties are not well understood yet. Here, we report the first experimental observation of two gaseous uranium hexachloride anions, UCl6 (-) and UCl6 (2-), which are probed by photoelectron spectroscopy in conjunction with quantum chemistry calculations. The electron affinity of UCl6 is measured for the first time as +5.3 eV; its second electron affinity is measured to be +0.60 eV from the photoelectron spectra of UCl6 (2-). We observe that the detachment cross sections of the 5f electrons are extremely weak in the visible and UV energy ranges. It is found that the one-electron one-determinental molecular orbital picture and Koopmans' theorem break down for the strongly internally correlated U-5f(2) valence shell of tetravalent U(+4) in UCl6 (2-). The calculated adiabatic and vertical electron detachment energies from ab initio calculations agree well with the experimental observations. Electronic structure and chemical bonding in the uranium hexachloride species UCl6 (2-) to UCl6 are discussed as a function of the oxidation state of U.
authors: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors: Jing
authors: J
authors: Su
authors: Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
authors: Phuong D
authors: PD
authors: Dau
authors: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors: Hong-Tao
authors: HT
authors: Liu
authors: Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
authors: Dao-Ling
authors: DL
authors: Huang
authors: Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084, China.
authors: Fan
authors: F
authors: Wei
authors: Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084, China.
authors: W H E
authors: WH
authors: Schwarz
authors: Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084, China.
authors: Jun
authors: J
authors: Li
authors: Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
authors: Lai-Sheng
authors: LS
authors: Wang