1 Investigation of Charge–transfer Absorptions in the Uranyl UO2 2+ (VI) Ion and Related Chemical Reduction of UO2 2+ (VI) to UO2 + (V) by UV-visible and Electron Paramagnetic Resonance Spectroscopies Xiaoping Sun,* 1 Derrick R. J. Kolling, 2 Hajer Mazagri, 1 Blake Karawan, 1 and Courtney Pierron 1 1. Department of Natural Sciences and Mathematics, University of Charleston, Charleston, West Virginia 25304, USA 2. Department of Chemistry, Marshall University, Huntington, West Virginia 25755, USA * To whom all the correspondence should be addressed. Phone: 1-304-357-4898 Fax: 1-304-357-4715 E-mail: xiaopingsun@ucwv.edu © 2015. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/