Scanning Tunneling Microscopy and Adsorption Studies on Single-Crystal Metal Oxide Surfaces

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dc.contributor.authorConway, Timothy Jamesen
dc.contributor.committeechairCox, David F.en
dc.contributor.committeememberConger, William L.en
dc.contributor.committeememberDavis, Richey M.en
dc.contributor.departmentChemical Engineeringen
dc.date.accessioned2014-03-14T20:52:28Zen
dc.date.adate1997-09-05en
dc.date.available2014-03-14T20:52:28Zen
dc.date.issued1997-09-01en
dc.date.rdate1998-09-05en
dc.date.sdate1997-09-01en
dc.description.abstractNatural and synthetic SnO₂ samples were studied using scanning tunneling microscopy (STM). The SnO₂ surface flattens considerably following high temperature treatments up to 1500 K. The conductivity of the synthetic SnO₂ surface is significantly reduced following annealing at temperatures of approximately 1200-1500 K, making tunneling impossible. A decrease in conductivity was not observed for the natural SnO₂ sample following similar high temperature treatments, most likely due to impurities which act as dopants. No atomic scale images were collected on the SnO₂ surface which provided information regarding atomic positions and point defects on the surface. Water adsorption was studied on the stoichiometric Cr₂O₃ (101̲2) surface, using thermal desorption spectroscopy (TDS). Water was the only desorption product observed during TDS. Adsorption is primarily dissociative following exposure to water at 163 K. Approximately, 0.12 monolayers of water dissociate on the clean, nearly stoichiometric Cr₂O₃ (101̲2) surface. The first order kinetics observed for the recombination of dissociated water are not well understood. One possible explanation is that the rate limiting step for desorption involves the breaking of a Cr-O bond resulting in a freely diffusing OH species. The exchange of halogen and oxygen was studied on Cr₂O₃ (101̲2) using Auger electron spectroscopy (AES) and TDS. The exchange of chlorine and oxygen is completely reversible. Chlorine is removed from the Cr₂O₃ (101̲2) surface following exposure to oxygen. Exposure of CFCl₂CH₂Cl reduces the surface oxygen concentration to that of the clean, nearly stoichiometric Cr₂O₃ (101̲2) surface. The exchange of chlorine with oxygen appears to involve only chemisorbed surface oxygen, not bulk lattice oxygen.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-8297-192718en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-8297-192718/en
dc.identifier.urihttp://hdl.handle.net/10919/37007en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartetd.pdfen
dc.relation.haspartacknow.pdfen
dc.relation.haspartintro.pdfen
dc.relation.haspartchp1.pdfen
dc.relation.haspartchp2.pdfen
dc.relation.haspartchp3.pdfen
dc.relation.haspartfuture.pdfen
dc.relation.haspartvita.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectmetal oxide surfacesen
dc.subjectscanning tunneling microscopyen
dc.titleScanning Tunneling Microscopy and Adsorption Studies on Single-Crystal Metal Oxide Surfacesen
dc.typeThesisen
thesis.degree.disciplineChemical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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