{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/77347"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/77347","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Probing the Surface of a Heterogeneous Catalyst: Double Resonance of Carbon Monoxide Chemisorbed on Highly Dispersed Platinum","abstract":"Spin Echo Double Resonance (SEDOR) is observed at 77 K for small Pt particles on which ('13)CO was chemisorbed. The samples are Pt supported on eta-alumina with Pt dispersions (fraction of the atoms that are on the surface) of 26% and 76%. After cleaning, the samples are exposed to CO enriched to 90% ('13)C. The ('13)C NMR is observed indirectly through its effect on the ('195)Pt spin echo. SEDOR allows the NMR of the surface ('195)Pt nuclei to be observed underneath the resonance of the nonsurface nuclei from which the surface nuclei are ordinarily unresolved. The position (1.096 kG/MHz)a and width (500 G at 80 kG) of the ('195)Pt SEDOR signal confirms the assignment by Rhodes et al. of a peak in the ('195)Pt NMR line shapes to the surface layer of platinum atoms. No surface nuclei are detected at any other locations in the ('195)Pt NMR line shape. Though the ('195)Pt NMR line shapes for the two dispersions are very different, the SEDOR line shapes are identical. SEDOR shows that the bonding of the CO is to the clean Pt surface through the carbon and that the Pt-C J coupling is similar to that in Pt carbonyls.","abstract_html":"Spin Echo Double Resonance (SEDOR) is observed at 77 K for small Pt particles on which ('13)CO was chemisorbed. The samples are Pt supported on eta-alumina with Pt dispersions (fraction of the atoms that are on the surface) of 26% and 76%. After cleaning, the samples are exposed to CO enriched to 90% ('13)C. The ('13)C NMR is observed indirectly through its effect on the ('195)Pt spin echo. SEDOR allows the NMR of the surface ('195)Pt nuclei to be observed underneath the resonance of the nonsurface nuclei from which the surface nuclei are ordinarily unresolved. The position (1.096 kG/MHz)a and width (500 G at 80 kG) of the ('195)Pt SEDOR signal confirms the assignment by Rhodes et al. of a peak in the ('195)Pt NMR line shapes to the surface layer of platinum atoms. No surface nuclei are detected at any other locations in the ('195)Pt NMR line shape. Though the ('195)Pt NMR line shapes for the two dispersions are very different, the SEDOR line shapes are identical. SEDOR shows that the bonding of the CO is to the clean Pt surface through the carbon and that the Pt-C J coupling is similar to that in Pt carbonyls.","abstract_has_math":false,"creators":["Makowka, Claus Dieter"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-05-13T15:41:34Z","date_published":"2015-05-13T15:41:34Z","updated_at":"2026-07-22T22:26:10Z","subjects":["Physics, Condensed Matter"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(UMI)AAI8218517"],"render_values":[{"text":"(UMI)AAI8218517","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/77347","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Makowka, Claus Dieter"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-05-13T15:41:34Z","10000-01-01","1982"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics, Condensed Matter"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/77347","(UMI)AAI8218517"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Spin Echo Double Resonance (SEDOR) is observed at 77 K for small Pt particles on which ('13)CO was chemisorbed. The samples are Pt supported on eta-alumina with Pt dispersions (fraction of the atoms that are on the surface) of 26% and 76%. After cleaning, the samples are exposed to CO enriched to 90% ('13)C. The ('13)C NMR is observed indirectly through its effect on the ('195)Pt spin echo. SEDOR allows the NMR of the surface ('195)Pt nuclei to be observed underneath the resonance of the nonsurface nuclei from which the surface nuclei are ordinarily unresolved. The position (1.096 kG/MHz)a and width (500 G at 80 kG) of the ('195)Pt SEDOR signal confirms the assignment by Rhodes et al. of a peak in the ('195)Pt NMR line shapes to the surface layer of platinum atoms. No surface nuclei are detected at any other locations in the ('195)Pt NMR line shape. Though the ('195)Pt NMR line shapes for the two dispersions are very different, the SEDOR line shapes are identical. SEDOR shows that the bonding of the CO is to the clean Pt surface through the carbon and that the Pt-C J coupling is similar to that in Pt carbonyls.","A phenomenological theory of the Knight shift in small platinum particles is developed to understand the Pt NMR line shapes. The theory successfully reproduces all the major features of the line shape data over the full range of dispersions studied by Rhodes et al. The theory has two principal assumptions. The first is that the 5d electron local density of states at the Fermi energy is reduced at the particle surface, healing exponentially to the bulk density of states on moving away from the surface. The second is treatment of the 6s electrons as free electrons confined to a spherical box, giving oscillations in the Knight shift. Surface nuclei give a distinct peak in agreement with the SEDOR results.","Made available in DSpace on 2015-05-13T15:41:34Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 8218517.PDF: 4098211 bytes, checksum: 9bceb6adf9c0fd30d5e5f78c9ef5ab07 (MD5) Previous issue date: 1982","Embargo set by: Seth Robbins for item 78558 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","154 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982."]},{"key":"dc:title","label":"Title","values":["Probing the Surface of a Heterogeneous Catalyst: Double Resonance of Carbon Monoxide Chemisorbed on Highly Dispersed Platinum"]}]}],"canonical_facts":{"dc:creator":["Makowka, Claus Dieter"],"dc:date":["2015-05-13T15:41:34Z","10000-01-01","1982"],"dc:description":["Spin Echo Double Resonance (SEDOR) is observed at 77 K for small Pt particles on which ('13)CO was chemisorbed. The samples are Pt supported on eta-alumina with Pt dispersions (fraction of the atoms that are on the surface) of 26% and 76%. After cleaning, the samples are exposed to CO enriched to 90% ('13)C. The ('13)C NMR is observed indirectly through its effect on the ('195)Pt spin echo. SEDOR allows the NMR of the surface ('195)Pt nuclei to be observed underneath the resonance of the nonsurface nuclei from which the surface nuclei are ordinarily unresolved. The position (1.096 kG/MHz)a and width (500 G at 80 kG) of the ('195)Pt SEDOR signal confirms the assignment by Rhodes et al. of a peak in the ('195)Pt NMR line shapes to the surface layer of platinum atoms. No surface nuclei are detected at any other locations in the ('195)Pt NMR line shape. Though the ('195)Pt NMR line shapes for the two dispersions are very different, the SEDOR line shapes are identical. SEDOR shows that the bonding of the CO is to the clean Pt surface through the carbon and that the Pt-C J coupling is similar to that in Pt carbonyls.","A phenomenological theory of the Knight shift in small platinum particles is developed to understand the Pt NMR line shapes. The theory successfully reproduces all the major features of the line shape data over the full range of dispersions studied by Rhodes et al. The theory has two principal assumptions. The first is that the 5d electron local density of states at the Fermi energy is reduced at the particle surface, healing exponentially to the bulk density of states on moving away from the surface. The second is treatment of the 6s electrons as free electrons confined to a spherical box, giving oscillations in the Knight shift. Surface nuclei give a distinct peak in agreement with the SEDOR results.","Made available in DSpace on 2015-05-13T15:41:34Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 8218517.PDF: 4098211 bytes, checksum: 9bceb6adf9c0fd30d5e5f78c9ef5ab07 (MD5) Previous issue date: 1982","Embargo set by: Seth Robbins for item 78558 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","154 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982."],"dc:identifier":["http://hdl.handle.net/2142/77347","(UMI)AAI8218517"],"dc:language":["eng"],"dc:subject":["Physics, Condensed Matter"],"dc:title":["Probing the Surface of a Heterogeneous Catalyst: Double Resonance of Carbon Monoxide Chemisorbed on Highly Dispersed Platinum"],"dc:type":["text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:10Z"}