{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/98182"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/98182","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Scanning tunneling microscopy investigation of atomically precise graphene nanoribbons","abstract":"This dissertation demonstrates the dry contact transfer of atomically precise graphene nanoribbons onto H:Si(100) under ultra-high vacuum, detailed electronic characterization, and electron-mediated polymerization of graphene nanoribbon precursors into polyanthrylene. Detailed scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements provided high-resolution imaging and reveal a 2.76 eV bandgap for chevron graphene nanoribbons. It was also discovered that tunneling to the substrate influenced STS measurements. STM and STS studies of two additional GNR geometries, the extended chevron GNR (eGNR) and the hybrid GNR (hGNR) elucidate how structural modification alters the bandgaps of GNRs. The increased lateral extension of the eGNR was found to result in a bandgap of 2.66 eV. The hGNR bandgap was found to be 1.8 eV, in agreement with computational modeling. The hypothesis that positional control over graphene nanoribbon synthesis could be achieved by tip-induced polymerization was explored. While the thermal self-assembly of 10,10′-dibromo-9,9′-bianthracene (DBBA) into N=7 armchair GNRs was previously demonstrated, the electron-mediated formation of polyanthrylene (GNR intermediate) formation was not previously shown. The STM experiments suggest that when the DBBA is thermally annealed to form a close-packed zigzag structure, an STM tip can be used to drive a de-bromination reaction which is followed by polyanthrylene formation, demonstrating a key step towards positional control over GNR synthesis.","abstract_html":"This dissertation demonstrates the dry contact transfer of atomically precise graphene nanoribbons onto H:Si(100) under ultra-high vacuum, detailed electronic characterization, and electron-mediated polymerization of graphene nanoribbon precursors into polyanthrylene. Detailed scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements provided high-resolution imaging and reveal a 2.76 eV bandgap for chevron graphene nanoribbons. It was also discovered that tunneling to the substrate influenced STS measurements. STM and STS studies of two additional GNR geometries, the extended chevron GNR (eGNR) and the hybrid GNR (hGNR) elucidate how structural modification alters the bandgaps of GNRs. The increased lateral extension of the eGNR was found to result in a bandgap of 2.66 eV. The hGNR bandgap was found to be 1.8 eV, in agreement with computational modeling. The hypothesis that positional control over graphene nanoribbon synthesis could be achieved by tip-induced polymerization was explored. While the thermal self-assembly of 10,10′-dibromo-9,9′-bianthracene (DBBA) into N=7 armchair GNRs was previously demonstrated, the electron-mediated formation of polyanthrylene (GNR intermediate) formation was not previously shown. The STM experiments suggest that when the DBBA is thermally annealed to form a close-packed zigzag structure, an STM tip can be used to drive a de-bromination reaction which is followed by polyanthrylene formation, demonstrating a key step towards positional control over GNR synthesis.","abstract_has_math":false,"creators":["Radocea, Adrian"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Materials Science & Engr","degree_department":null,"school":null,"contributors":["Lyding, Joseph W.","Girolami, Gregory","Shim, Moonsub","Huang, Pinshane","Schleife, André"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2017,"date_issued":"2017-09-29T17:45:28Z","date_published":"2017-09-29T17:45:28Z","updated_at":"2026-07-22T22:24:35Z","subjects":["Graphene","Graphene Nanoribbons","Scanning tunneling microscopy","Scanning tunneling spectroscopy","Silicon","Polyanthrylene","10,10′-dibromo-9,9′-bianthracene (DBBA)"],"languages":["en"],"rights":["Copyright 2017 Adrian Radocea"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/98182","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lyding, Joseph W.","Girolami, Gregory","Shim, Moonsub","Huang, Pinshane","Schleife, André"]},{"key":"dc:creator","label":"Author","values":["Radocea, Adrian"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2017-09-29T17:45:28Z","2020-03-03T10:15:35Z","2017-06-26","2017-08"]},{"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":["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":["Graphene","Graphene Nanoribbons","Scanning tunneling microscopy","Scanning tunneling spectroscopy","Silicon","Polyanthrylene","10,10′-dibromo-9,9′-bianthracene (DBBA)"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2017 Adrian Radocea"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/98182"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["This dissertation demonstrates the dry contact transfer of atomically precise graphene nanoribbons onto H:Si(100) under ultra-high vacuum, detailed electronic characterization, and electron-mediated polymerization of graphene nanoribbon precursors into polyanthrylene. Detailed scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements provided high-resolution imaging and reveal a 2.76 eV bandgap for chevron graphene nanoribbons. It was also discovered that tunneling to the substrate influenced STS measurements. STM and STS studies of two additional GNR geometries, the extended chevron GNR (eGNR) and the hybrid GNR (hGNR) elucidate how structural modification alters the bandgaps of GNRs. The increased lateral extension of the eGNR was found to result in a bandgap of 2.66 eV. The hGNR bandgap was found to be 1.8 eV, in agreement with computational modeling. The hypothesis that positional control over graphene nanoribbon synthesis could be achieved by tip-induced polymerization was explored. While the thermal self-assembly of 10,10′-dibromo-9,9′-bianthracene (DBBA) into N=7 armchair GNRs was previously demonstrated, the electron-mediated formation of polyanthrylene (GNR intermediate) formation was not previously shown. The STM experiments suggest that when the DBBA is thermally annealed to form a close-packed zigzag structure, an STM tip can be used to drive a de-bromination reaction which is followed by polyanthrylene formation, demonstrating a key step towards positional control over GNR synthesis.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-08-01","The student, Adrian Radocea, accepted the attached license on 2017-06-23 at 15:40.","The student, Adrian Radocea, submitted this Dissertation for approval on 2017-06-23 at 15:53.","This Dissertation was approved for publication on 2017-06-26 at 10:44.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11261 on 2017-09-29 at 10:46:05","Made available in DSpace on 2017-09-29T17:45:28Z (GMT). No. of bitstreams: 4 RADOCEA-DISSERTATION-2017.pdf: 14315081 bytes, checksum: bae451b3ff5d557f1eb42695893a357b (MD5) LICENSE.txt: 4211 bytes, checksum: 786ada4296669df94004adce9bd348cb (MD5) Nano Letters Chevron.pdf: 307729 bytes, checksum: f52f0105e1c6ddcd342ee2e20aa7e20e (MD5) Nano Letters Chevron_pg2.pdf: 296598 bytes, checksum: 89d488a1f1e542aa4577680b49e4417d (MD5) Previous issue date: 2017-06-26","Embargo set by: Colleen Fallaw for item 103472 Lift date: 2019-09-29T17:48:06Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 103472 Lift date: 2020-03-02T19:56:41Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 103472 Lift date: 2020-03-02T19:59:52Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 103472 Lift date: 2020-03-02T20:02:46Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 103472 on 2020-03-03T10:15:35Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Scanning tunneling microscopy investigation of atomically precise graphene nanoribbons"]}]}],"canonical_facts":{"dc:contributor":["Lyding, Joseph W.","Girolami, Gregory","Shim, Moonsub","Huang, Pinshane","Schleife, André"],"dc:creator":["Radocea, Adrian"],"dc:date":["2017-09-29T17:45:28Z","2020-03-03T10:15:35Z","2017-06-26","2017-08"],"dc:description":["This dissertation demonstrates the dry contact transfer of atomically precise graphene nanoribbons onto H:Si(100) under ultra-high vacuum, detailed electronic characterization, and electron-mediated polymerization of graphene nanoribbon precursors into polyanthrylene. Detailed scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements provided high-resolution imaging and reveal a 2.76 eV bandgap for chevron graphene nanoribbons. It was also discovered that tunneling to the substrate influenced STS measurements. STM and STS studies of two additional GNR geometries, the extended chevron GNR (eGNR) and the hybrid GNR (hGNR) elucidate how structural modification alters the bandgaps of GNRs. The increased lateral extension of the eGNR was found to result in a bandgap of 2.66 eV. The hGNR bandgap was found to be 1.8 eV, in agreement with computational modeling. The hypothesis that positional control over graphene nanoribbon synthesis could be achieved by tip-induced polymerization was explored. While the thermal self-assembly of 10,10′-dibromo-9,9′-bianthracene (DBBA) into N=7 armchair GNRs was previously demonstrated, the electron-mediated formation of polyanthrylene (GNR intermediate) formation was not previously shown. The STM experiments suggest that when the DBBA is thermally annealed to form a close-packed zigzag structure, an STM tip can be used to drive a de-bromination reaction which is followed by polyanthrylene formation, demonstrating a key step towards positional control over GNR synthesis.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-08-01","The student, Adrian Radocea, accepted the attached license on 2017-06-23 at 15:40.","The student, Adrian Radocea, submitted this Dissertation for approval on 2017-06-23 at 15:53.","This Dissertation was approved for publication on 2017-06-26 at 10:44.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11261 on 2017-09-29 at 10:46:05","Made available in DSpace on 2017-09-29T17:45:28Z (GMT). No. of bitstreams: 4 RADOCEA-DISSERTATION-2017.pdf: 14315081 bytes, checksum: bae451b3ff5d557f1eb42695893a357b (MD5) LICENSE.txt: 4211 bytes, checksum: 786ada4296669df94004adce9bd348cb (MD5) Nano Letters Chevron.pdf: 307729 bytes, checksum: f52f0105e1c6ddcd342ee2e20aa7e20e (MD5) Nano Letters Chevron_pg2.pdf: 296598 bytes, checksum: 89d488a1f1e542aa4577680b49e4417d (MD5) Previous issue date: 2017-06-26","Embargo set by: Colleen Fallaw for item 103472 Lift date: 2019-09-29T17:48:06Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 103472 Lift date: 2020-03-02T19:56:41Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 103472 Lift date: 2020-03-02T19:59:52Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 103472 Lift date: 2020-03-02T20:02:46Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 103472 on 2020-03-03T10:15:35Z."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/98182"],"dc:language":["en"],"dc:rights":["Copyright 2017 Adrian Radocea"],"dc:subject":["Graphene","Graphene Nanoribbons","Scanning tunneling microscopy","Scanning tunneling spectroscopy","Silicon","Polyanthrylene","10,10′-dibromo-9,9′-bianthracene (DBBA)"],"dc:title":["Scanning tunneling microscopy investigation of atomically precise graphene nanoribbons"],"dc:type":["text"],"thesis:degree_discipline":["Materials Science & Engr"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:35Z"}