{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/22107"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/22107","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Measurement of the chemical potential of thin helium films","abstract":"High-precision measurements of third sound velocities in atomically thin $\\sp4$He films on Ar, Ne, CO$\\sb2$, and H$\\sb2$ substrates in the T = OK limit reveal a periodic structure not corresponding to whole layers. We analyze the data in two extreme limits. First, treating the helium film as an incompressible, continuous fluid, the data indicate that the chemical potential has a contribution proportional to $\\ell\\sp{-6}$, where $\\ell$ is a layer coverage, which is modulated at intervals of.62 $\\pm$.04 layers, and which weakens the van der Waals potential. Second, if we assume the potential is exactly the van der Waals potential, the data indicate the existence in the film of a damped smectic density wave with a periodicity of.54 $\\pm$.04 layers, independent of substrate. The correct description of He films must lie between these extremes. We find the inert layer coverages to be 1 full layer on Ar, Ne, and CO$\\sb2$, and.36 layers on H$\\sb2$.","abstract_html":"High-precision measurements of third sound velocities in atomically thin $\\sp4$He films on Ar, Ne, CO$\\sb2$, and H$\\sb2$ substrates in the T = OK limit reveal a periodic structure not corresponding to whole layers. We analyze the data in two extreme limits. First, treating the helium film as an incompressible, continuous fluid, the data indicate that the chemical potential has a contribution proportional to $\\ell\\sp{-6}$, where $\\ell$ is a layer coverage, which is modulated at intervals of.62 $\\pm$.04 layers, and which weakens the van der Waals potential. Second, if we assume the potential is exactly the van der Waals potential, the data indicate the existence in the film of a damped smectic density wave with a periodicity of.54 $\\pm$.04 layers, independent of substrate. The correct description of He films must lie between these extremes. We find the inert layer coverages to be 1 full layer on Ar, Ne, and CO$\\sb2$, and.36 layers on H$\\sb2$.","abstract_has_math":true,"creators":["Shirron, Peter John"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Mochel, J.M."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T13:29:10Z","date_published":"2011-05-07T13:29:10Z","updated_at":"2026-07-22T22:25:19Z","subjects":["Physics, Condensed Matter"],"languages":["eng"],"rights":["Copyright 1989 Shirron, Peter John"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9011023","(UMI)AAI9011023"],"render_values":[{"text":"AAI9011023","href":null,"code":true},{"text":"(UMI)AAI9011023","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/22107","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Mochel, J.M."]},{"key":"dc:creator","label":"Author","values":["Shirron, Peter John"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T13:29:10Z","10000-01-01","1989"]},{"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"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1989 Shirron, Peter John"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9011023","(UMI)AAI9011023","http://hdl.handle.net/2142/22107"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["High-precision measurements of third sound velocities in atomically thin $\\sp4$He films on Ar, Ne, CO$\\sb2$, and H$\\sb2$ substrates in the T = OK limit reveal a periodic structure not corresponding to whole layers. We analyze the data in two extreme limits. First, treating the helium film as an incompressible, continuous fluid, the data indicate that the chemical potential has a contribution proportional to $\\ell\\sp{-6}$, where $\\ell$ is a layer coverage, which is modulated at intervals of.62 $\\pm$.04 layers, and which weakens the van der Waals potential. Second, if we assume the potential is exactly the van der Waals potential, the data indicate the existence in the film of a damped smectic density wave with a periodicity of.54 $\\pm$.04 layers, independent of substrate. The correct description of He films must lie between these extremes. We find the inert layer coverages to be 1 full layer on Ar, Ne, and CO$\\sb2$, and.36 layers on H$\\sb2$.","Coverages scales were determined using helium adsorption isotherms. A self-consistent analysis method was developed based on the modified Brunauer-Emmet-Teller method for low coverages and the Fenkel-Halsey-Hill vapor pressure relation at high coverages. The analysis establishes the layer capacities for helium films and helium-substrate chemical potential constants, $\\Gamma$.","Made available in DSpace on 2011-05-07T13:29:10Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9011023.pdf: 5493040 bytes, checksum: 4a7094e755d313d74d3e4e857e23a68a (MD5) Previous issue date: 1989","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:55:22Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:25:48-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"]},{"key":"dc:title","label":"Title","values":["Measurement of the chemical potential of thin helium films"]}]}],"canonical_facts":{"dc:contributor":["Mochel, J.M."],"dc:creator":["Shirron, Peter John"],"dc:date":["2011-05-07T13:29:10Z","10000-01-01","1989"],"dc:description":["High-precision measurements of third sound velocities in atomically thin $\\sp4$He films on Ar, Ne, CO$\\sb2$, and H$\\sb2$ substrates in the T = OK limit reveal a periodic structure not corresponding to whole layers. We analyze the data in two extreme limits. First, treating the helium film as an incompressible, continuous fluid, the data indicate that the chemical potential has a contribution proportional to $\\ell\\sp{-6}$, where $\\ell$ is a layer coverage, which is modulated at intervals of.62 $\\pm$.04 layers, and which weakens the van der Waals potential. Second, if we assume the potential is exactly the van der Waals potential, the data indicate the existence in the film of a damped smectic density wave with a periodicity of.54 $\\pm$.04 layers, independent of substrate. The correct description of He films must lie between these extremes. We find the inert layer coverages to be 1 full layer on Ar, Ne, and CO$\\sb2$, and.36 layers on H$\\sb2$.","Coverages scales were determined using helium adsorption isotherms. A self-consistent analysis method was developed based on the modified Brunauer-Emmet-Teller method for low coverages and the Fenkel-Halsey-Hill vapor pressure relation at high coverages. The analysis establishes the layer capacities for helium films and helium-substrate chemical potential constants, $\\Gamma$.","Made available in DSpace on 2011-05-07T13:29:10Z (GMT). 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