A New Approach to the Study of Surface Phenomena: Measurements of Diffusion Rates, Intermolecular Distances and Electronic Properties of Carbon Monoxide Chemisorbed on Supported Platinum Catalysts by Nuclear Magnetic Resonance

185 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.The author has applied magnetic resonance to study the chemisorption of CO on supported platinum particles. The particles are 10 to 50 (ANGSTROM) in diameter, supported on alumina. CO is 90% enriched with ('13)CO. NMR data were taken from 4 K to 600 K.He shows that a measurement of transverse relaxation at 77 K can be used to measure relative distances among molecules in the adsorbed layer. His measurements of transverse relaxation and of spin-lattice relaxation are consistent with the geometry of CO layers chemisorbed on single crystal surfaces.He has observed the narrowing of the NMR line and the effects of motion on transverse relaxation from 300 K to 600 K from which he deduces diffusion energies of 13 and 16 (+OR-) 2 kcal/mol, in agreement with measurement of R. Lewis and R. Gomer of the diffusion of CO on Pt tips by Field Emission Microscopy.He demonstrates that conduction electrons are present on CO and shows that the distribution of spin-lattice relaxation times observed at 77 K reflects the various binding configurations present at the surface of each particle, irrespective of the particle size.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD