Combination of uranium, peroxide, and mono- (Na, K) or divalent (Mg, Ca, Sr) cations under alkaline aqueous conditions results in the rapid formation of anionic uranyl triperoxide monomers (UTs), (UO2(O2)3)4-, exhibiting unique Raman signatures. Electronic structure calculations were decisive for the interpretation of the spectra and assignment of unexpected signals associated with vibrations of the uranyl and peroxide ions. Assignments were verified by 18O isotopic labeling of the uranyl ions supporting the computational-based interpretation of the experimentally observed peaks and the assignment of a novel asymmetric vibration of the peroxide ligands, v2(O2 2-).
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This work was supported by the Office of Basic Energy Sciences of the U.S. Department of Energy as part of the Materials Science of Actinides Energy Frontiers Center (DESC0001089). Raman spectroscopy measurements were conducted at the Materials Characterization Facility of the Center for Sustainable Energy at the University of Notre Dame. ICPOES measurements were conducted at the Center for Environmental Science and Technology at the University of Notre Dame.