The U+O chemi-ionization reaction has been investigated by quantum chemical methods. Potential-energy curves have been calculated for several electronic states of UO and U O+. Comparison with the available spectroscopic and thermodynamic values for these species is reported and a mechanism for the chemi-ionization reaction U+O→U O+ + e- is proposed. The U+O and Sm+O chemi-ionization reactions are the first two metal-plus-oxidant chemi-ionization reactions to be studied theoretically in this way.
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The authors wish to thank Professor Björn Olof Roos for ANO-RCC basis set for U and for valuable advice. This research was supported in part by a Grant-in-Aid for Scientific Research in Specially Promoted Research “Simulations and Dynamics for Real Systems” and Grant for 21st Century COE Program “Human-Friendly Materials based on Chemistry” from the Ministry of Education, Science, Culture, and Sports of Japan, and by a grant from the Genesis Research Institute. One of the authors (J.P.) is grateful for a financial support from the Ministry of Education, Science, Culture, and Sports of Japan. The authors are grateful for excellent computational facilities at the University of Tokyo. One of the authors (J.M.D.) thanks the NERC (UK) for financial support. One of the authors (L.G.) thanks Ministero dell’Istruzione dell’Universita’e della Ricerca (MIUR) for financial support.