{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/45578"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/45578","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Thermal transport across interfaces with molecular layers","abstract":"This thesis presents the experimental study of thermal transport across molecular interfaces. Molecular interfaces are fabricated by assembling Au nanocrystals with controllable surface chemistry onto oxide substrates such as quartz and sapphire. A self-assembled monolayer (SAM) of silane molecules is also grown on sapphire to make the third variety of molecular interfaces. The technique of transient absorption (TA) is used to probe the evolution of Au temperature following abrupt heating by an optical pulse. I modeled the heat transfer from the Au nanocrystals into the molecular coating and then to the substrate and I obtained the values of interfacial thermal conductance of Au/cetyl trimethylammonium bromide/quartz and Au/16-mercapto trimethylammonium bromide/quartz in the temperature range of 40 < T < 300 K. The room temperature thermal conductance (G) values of these interfaces are both 150 ± 15 MW m-2K-1. Low temperature measurements are carried out in an optical cryostat and the temperature dependence of G(T) is found to have the same form as the temperature dependence of the heat capacity of Au. These results suggest the spectrum of vibrational modes that carry heat through the molecular interfaces is similar to the vibrational spectrum of Au; and that anharmonicity does not significantly contribute to the heat transport in this system.","abstract_html":"This thesis presents the experimental study of thermal transport across molecular interfaces. Molecular interfaces are fabricated by assembling Au nanocrystals with controllable surface chemistry onto oxide substrates such as quartz and sapphire. A self-assembled monolayer (SAM) of silane molecules is also grown on sapphire to make the third variety of molecular interfaces. The technique of transient absorption (TA) is used to probe the evolution of Au temperature following abrupt heating by an optical pulse. I modeled the heat transfer from the Au nanocrystals into the molecular coating and then to the substrate and I obtained the values of interfacial thermal conductance of Au/cetyl trimethylammonium bromide/quartz and Au/16-mercapto trimethylammonium bromide/quartz in the temperature range of 40 &lt; T &lt; 300 K. The room temperature thermal conductance (G) values of these interfaces are both 150 ± 15 MW m-2K-1. Low temperature measurements are carried out in an optical cryostat and the temperature dependence of G(T) is found to have the same form as the temperature dependence of the heat capacity of Au. These results suggest the spectrum of vibrational modes that carry heat through the molecular interfaces is similar to the vibrational spectrum of Au; and that anharmonicity does not significantly contribute to the heat transport in this system.","abstract_has_math":false,"creators":["Wang, Wei"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Materials Science & Engr","degree_department":null,"school":null,"contributors":["Cahill, David G."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2013,"date_issued":"2013-08-22T16:48:25Z","date_published":"2013-08-22T16:48:25Z","updated_at":"2026-07-22T22:25:36Z","subjects":["Thermal transport","interfaces with molecules","ultrafast","transient absorption","temperature dependence","self-assembled monolayer (SAM)."],"languages":["en"],"rights":["Copyright 2013 Wei Wang"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/45578","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Cahill, David G."]},{"key":"dc:creator","label":"Author","values":["Wang, Wei"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2013-08-22T16:48:25Z","2015-08-22T10:00:40Z","2013-08"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Science & Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"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":["Thermal transport","interfaces with molecules","ultrafast","transient absorption","temperature dependence","self-assembled monolayer (SAM)."]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2013 Wei Wang"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/45578"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["This thesis presents the experimental study of thermal transport across molecular interfaces. Molecular interfaces are fabricated by assembling Au nanocrystals with controllable surface chemistry onto oxide substrates such as quartz and sapphire. A self-assembled monolayer (SAM) of silane molecules is also grown on sapphire to make the third variety of molecular interfaces. The technique of transient absorption (TA) is used to probe the evolution of Au temperature following abrupt heating by an optical pulse. I modeled the heat transfer from the Au nanocrystals into the molecular coating and then to the substrate and I obtained the values of interfacial thermal conductance of Au/cetyl trimethylammonium bromide/quartz and Au/16-mercapto trimethylammonium bromide/quartz in the temperature range of 40 < T < 300 K. The room temperature thermal conductance (G) values of these interfaces are both 150 ± 15 MW m-2K-1. Low temperature measurements are carried out in an optical cryostat and the temperature dependence of G(T) is found to have the same form as the temperature dependence of the heat capacity of Au. These results suggest the spectrum of vibrational modes that carry heat through the molecular interfaces is similar to the vibrational spectrum of Au; and that anharmonicity does not significantly contribute to the heat transport in this system.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2013-07-17T20:49:35Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 THESIS FORMATTED.docx: 2578199 bytes, checksum: d3863d2286ac97f3c027553c6f20f012 (MD5) Wang_Wei.pdf: 1086607 bytes, checksum: ae1ac93c2fcc7e52a3c88fd2b779dd14 (MD5)","Made available in DSpace on 2013-08-22T16:48:25Z (GMT). No. of bitstreams: 3 Wei_Wang.pdf: 1086607 bytes, checksum: ae1ac93c2fcc7e52a3c88fd2b779dd14 (MD5) THESIS FORMATTED.docx: 2578199 bytes, checksum: d3863d2286ac97f3c027553c6f20f012 (MD5) license.txt: 4057 bytes, checksum: 37f8765fd2ef54e36ebaed17f71d2ab4 (MD5)","Restriction data tranferred 2014-07-01T11:21:14-05:00 Original Data Group with Access UIUC Users [automated] Release Date: 2015-08-22 11:49:27 UTC Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Seth Robbins (srobbins@illinois.edu) on 2013-08-22T16:49:39Z Item is restricted until 2015-08-22T16:49:27Z","U of I Only Restriction Lifted for Item 45560 on 2015-08-22T10:00:40Z."]},{"key":"dc:title","label":"Title","values":["Thermal transport across interfaces with molecular layers"]}]}],"canonical_facts":{"dc:contributor":["Cahill, David G."],"dc:creator":["Wang, Wei"],"dc:date":["2013-08-22T16:48:25Z","2015-08-22T10:00:40Z","2013-08"],"dc:description":["This thesis presents the experimental study of thermal transport across molecular interfaces. Molecular interfaces are fabricated by assembling Au nanocrystals with controllable surface chemistry onto oxide substrates such as quartz and sapphire. A self-assembled monolayer (SAM) of silane molecules is also grown on sapphire to make the third variety of molecular interfaces. The technique of transient absorption (TA) is used to probe the evolution of Au temperature following abrupt heating by an optical pulse. I modeled the heat transfer from the Au nanocrystals into the molecular coating and then to the substrate and I obtained the values of interfacial thermal conductance of Au/cetyl trimethylammonium bromide/quartz and Au/16-mercapto trimethylammonium bromide/quartz in the temperature range of 40 < T < 300 K. The room temperature thermal conductance (G) values of these interfaces are both 150 ± 15 MW m-2K-1. Low temperature measurements are carried out in an optical cryostat and the temperature dependence of G(T) is found to have the same form as the temperature dependence of the heat capacity of Au. These results suggest the spectrum of vibrational modes that carry heat through the molecular interfaces is similar to the vibrational spectrum of Au; and that anharmonicity does not significantly contribute to the heat transport in this system.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2013-07-17T20:49:35Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 THESIS FORMATTED.docx: 2578199 bytes, checksum: d3863d2286ac97f3c027553c6f20f012 (MD5) Wang_Wei.pdf: 1086607 bytes, checksum: ae1ac93c2fcc7e52a3c88fd2b779dd14 (MD5)","Made available in DSpace on 2013-08-22T16:48:25Z (GMT). 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