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Title: Spectroscopic and theoretical studies of UN and UN +

Journal Article · · Journal of Chemical Physics
DOI:https://doi.org/10.1063/1.5144299· OSTI ID:1632833
 [1]; ORCiD logo [2]; ORCiD logo [1];  [3];  [3]; ORCiD logo [3]
  1. Washington State Univ., Pullman, WA (United States)
  2. Argonne National Lab. (ANL), Lemont, IL (United States)
  3. Emory Univ., Atlanta, GA (United States)
+ Show Author Affiliations

The low energy electronic states of UN and UN+ have been examined using high-level electronic structure calculations and two-color photoionization techniques. The experimental measurements provided an accurate ionization energy for UN (IE=50802±5 cm-1). Spectra for UN+ yielded ro-vibrational constants and established that the ground state has the electronic angular momentum projection Ω=4. Ab initio calculations were carried out using the spin-orbit state interacting approach with the complete active space 2nd-order perturbation theory (CASPT2) method. A series of correlation consistent basis sets were used in conjunction with small-core relativistic pseudopotentials on U to extrapolate to the complete basis set (CBS) limits. The results for UN correctly obtained an Ω=3.5 ground state and demonstrated a high density of configurationally related excited states with closely similar ro-vibrational constants. Similar results were obtained for UN+, with reduced complexity owing to the smaller number of outer-shell electrons. The calculated IE for UN was in excellent agreement with the measured value. Improved values for the dissociation energies of UN and UN+, as well as their heats of formation, were obtained using the Feller-Peterson-Dixon composite thermochemistry method including corrections up through CCSDTQ. An analysis of the ab initio results from the perspective of ligand field theory shows that the patterns of electronic states for both UN and UN+ can be understood in terms of the underlying energy level structure of the atomic metal ion.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States); Emory Univ., Atlanta, GA (United States); Washington State Univ., Pullman, WA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC02-06CH11357; SC0008501; FG02-01ER15153
OSTI ID:
1632833
Alternate ID(s):
OSTI ID: 1602343; OSTI ID: 1773730
Journal Information:
Journal of Chemical Physics, Vol. 152, Issue 9; ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 12 works
Citation information provided by
Web of Science

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