Whitehead, Christopher Breck, authorFinke, Richard, advisorNeilson, Jamie, committee memberVan Orden, Alan, committee memberShipman, Patrick, committee member2021-06-072022-06-022021https://hdl.handle.net/10217/232586A long-sought goal in particle formation is an understanding of the chemical reaction mechanism. The complete understanding of the associated processes (nucleation, growth, and agglomeration) will yield particle size and distribution control. Mechanistic control and knowledge will yield improvements in the development of renewable energy and catalytic materials. The current state of chemical reaction mechanisms and the direct methods to study them are presented in an in-depth literature review in Chapter II. The best, state-of-the-art case studies are examined and the minimum criteria for a reliable, disproof-based chemical mechanism are presented. The experimental work presented in this dissertation centers on a second-generation {[(1,5-COD)IrI•HPO4]2}2– precursor to Ir(0)~150(HPO42–)x nanoparticle system. The exhaustive investigation of the reaction speciation and the dependence of IrI and HPO42– concentrations on the reaction kinetics are presented in Chapter III. Based on the reaction kinetics and there experimentally determined nucleation step, the molecular mechanism of Ir(0)~150(HPO42–)x nanoparticle formation is elucidated. Next, in Chapter IV, the second-generation {[(1,5-COD)IrI•HPO4]2}2– precursor to Ir(0)~150(HPO42–)x nanoparticle system is monitored directly by X-ray absorption spectroscopy and small-angle X-ray scattering and indirectly by in-house cyclohexene reporter reaction, gas-liquid chromatography, proton nuclear magnetic resonance, and transmission electron microscopy. A total of 6 physical methods are used to follow the particle formation kinetics. Finally, mechanism-enabled population balance modeling is applied as a final test of the proposed mechanism.born digitaldoctoral dissertationsengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.iridiumnanoparticledisproof-basednucleationmechanismText