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Title: Negative Ion Photoelectron Spectroscopy Confirms the Prediction that D-3h Carbontrioxide (CO 3) Has a Singlet Ground State

The CO 3 radical anion (CO 3 •–) has been formed by electrospraying carbonate dianion (CO 3 2–) into the gas phase. The negative ion photoelectron (NIPE) spectrum of CO 3 •– shows that, unlike trimethylenemethane [C(CH 2) 3], carbontrioxide (CO 3) has a singlet ground state. From the NIPE spectrum, the electron affinity of CO 3 was determined to be EA = 4.06 ± 0.03 eV, and the singlet-triplet energy difference was found to be ΔEST = - 17.8 ± 0.9 kcal/mol. B3LYP, CCSD(T), and CASPT2 calculations all find that the two lowest triplet states of CO 3 are very close in energy, a prediction that is confirmed by the relative intensities of the bands in the NIPE spectrum of CO 3 •–. The 560 cm -1 vibrational progression, seen in the low energy region of the triplet band, enables the identification of the lowest, Jahn-Teller-distorted, triplet state as 3A 1, in which both unpaired electrons reside in σ MOs, rather than 3A 2, in which one unpaired electron occupies the b 2 σ MO, and the other occupies the b 1 π MO.
 [1] ;  [2] ;  [1] ;  [2] ;  [1]
  1. Univ. of North Texas, Denton, TX (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2041-6520; 48584; KC0301050
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 7; Journal Issue: 2; Journal ID: ISSN 2041-6520
Royal Society of Chemistry
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org:
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Environmental Molecular Sciences Laboratory
OSTI Identifier: