b'Intrinsic bonding andResearchers establish unique capability that enables easier reactivity of actinide clusters exploration of heavy transuranic element chemistry.T he effect of electronic structure on chemical bonding and reactivity is one of the most important questions in the field of chemistry. Insight into chemical bond formation involving elements that contain f electrons (i.e., the lanthanides and actinides) is critical for solving specific technical challenges, such as development of advanced nuclear fuel cycles and efficient rare earth PROJECT NUMBER:separations, as well as a broader understanding of bonding across the entire periodic 21A1057-017FP table. The primary technique for studying the fundamentals of lanthanide and actinide bonding is crystallization of metal-ligand compounds followed by structural TOTAL APPROVED AMOUNT:determination with x-rays and comparison to theory with computational chemistry. $285,500 over 3 years While this procedure has yielded significant insights for a wide variety of elements, PRINCIPAL INVESTIGATOR:it is challenging to apply to the heavier transuranic actinides such as berkelium and Christopher Zarzana californium because of limited material availability, significant radioactivity, and poorly understood chemical reactivity of these elements. In contrast, gas phase CO-INVESTIGATORS: actinide-ligand complexes can be formed in a mass spectrometer from extremely Hodges, Brittany, INL small quantities of starting material, enabling easier exploration of the chemistry of Holmbeck, Gregory, INL the heavy transuranic elements. This project successfully established the capability to Christian Celis-Barros, Florida State University conduct experiments with transuranic actinides in a trapping atmospheric pressure ionization mass spectrometer at INL. These experimental results can have important implications for theoretical calculation and modeling transuranic elements, which are difficult to study. By providing experimental data, theoreticians can refine and improve models that apply to fuel cycles, storage of used nuclear fuels, and environmental management of transuranic elements. As far as we know, this represents only the third such instrument in the world and is a new capability at INL for studying chemistry at the very edges of the periodic table.126'