{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/22541"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/22541","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Proton-coupled carbon-13 sample spinning NMR studies of macromolecules and ordered systems","abstract":"\"We have studied a variety of macromolecular systems such as lipid/water lyotropic phases and elastomeric polymers, and in addition a thermotropic liquid-crystal displaying macroscopic orientational ordering behavior, by Carbon-13 ($\\sp{13}$C) nuclear magnetic resonance (NMR) spectroscopy. We find that under \"\"magic angle\"\" spinning (MAS) these systems display high resolution due to extensive motions, and therefore traditional proton-decoupling is not necessary. In the absence of proton decoupling, i.e., proton-coupled MAS (PCMAS), we find that these systems display scalar hyperfine-coupled $\\sp{13}$C splittings with radically asymmetric linewidths and shapes. We attribute these effects to cross-correlation terms between two or more different relaxation mechanisms, (dipolar/chemical shift anisotropy (DD/CSA) relaxations) at the high magnetic fields employed.\"","abstract_html":""We have studied a variety of macromolecular systems such as lipid/water lyotropic phases and elastomeric polymers, and in addition a thermotropic liquid-crystal displaying macroscopic orientational ordering behavior, by Carbon-13 ($\\sp{13}$C) nuclear magnetic resonance (NMR) spectroscopy. We find that under ""magic angle"" spinning (MAS) these systems display high resolution due to extensive motions, and therefore traditional proton-decoupling is not necessary. In the absence of proton decoupling, i.e., proton-coupled MAS (PCMAS), we find that these systems display scalar hyperfine-coupled $\\sp{13}$C splittings with radically asymmetric linewidths and shapes. We attribute these effects to cross-correlation terms between two or more different relaxation mechanisms, (dipolar/chemical shift anisotropy (DD/CSA) relaxations) at the high magnetic fields employed."","abstract_has_math":true,"creators":["Chung, John"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":["Oldfield, Eric"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T13:43:11Z","date_published":"2011-05-07T13:43:11Z","updated_at":"2026-07-22T22:25:20Z","subjects":["Chemistry, Physical"],"languages":["eng"],"rights":["Copyright 1991 Chung, John"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9210769","(UMI)AAI9210769"],"render_values":[{"text":"AAI9210769","href":null,"code":true},{"text":"(UMI)AAI9210769","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/22541","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Oldfield, Eric"]},{"key":"dc:creator","label":"Author","values":["Chung, John"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T13:43:11Z","10000-01-01","1991"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemistry"]},{"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":["Chemistry, Physical"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1991 Chung, John"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9210769","(UMI)AAI9210769","http://hdl.handle.net/2142/22541"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["\"We have studied a variety of macromolecular systems such as lipid/water lyotropic phases and elastomeric polymers, and in addition a thermotropic liquid-crystal displaying macroscopic orientational ordering behavior, by Carbon-13 ($\\sp{13}$C) nuclear magnetic resonance (NMR) spectroscopy. We find that under \"\"magic angle\"\" spinning (MAS) these systems display high resolution due to extensive motions, and therefore traditional proton-decoupling is not necessary. In the absence of proton decoupling, i.e., proton-coupled MAS (PCMAS), we find that these systems display scalar hyperfine-coupled $\\sp{13}$C splittings with radically asymmetric linewidths and shapes. We attribute these effects to cross-correlation terms between two or more different relaxation mechanisms, (dipolar/chemical shift anisotropy (DD/CSA) relaxations) at the high magnetic fields employed.\"","Since the DD/CSA effects are quite novel and have not been treated in detail experimentally or theoretically, we have extended the previous theories to a more realistic anisotropic motional model and have attempted to explain the proton-coupled $\\sp{13}$C longitudinal relaxation data in two elastomers by fitting it to the simple model. The data does not explain the model in an intuitively reasonable fashion; and it is concluded that more work needs to be done in order to study a system with more experimental measurables which would allow for fitting to a more elaborate theory of restricted motions.","\"We have also tried to extend the usefulness of PC-MAS relaxation cross-correlation study to a thermotropic liquid crystal; and in the process we have determined the effects which sample spinning in a magnetic field can have on an ordered phase such as the nematic phase of a liquid crystal. Our findings indicate that rapid spinning of the sample can lead to destruction of the macroscopic order-director alignment along the sample spinner axis. In order to avoid this difficulty \"\"off-axis\"\" spinning experiments are done to show that the stability of the order director can be maintained. With the added precaution we show that proton-coupled $\\sp{13}$C relaxation study is feasible in the nematic phase; and from the measured relaxation time constants we obtain macroscopic cross-correlation spectral densities, although the interpretation of these spectral densities is dependent on the of knowledge of the accurate static tensor elements.\"","Made available in DSpace on 2011-05-07T13:43:11Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9210769.pdf: 3993379 bytes, checksum: 8760939145d3218d6373cbbbb36427c9 (MD5) Previous issue date: 1991","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:58:19Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:27:25-05:00 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":["Proton-coupled carbon-13 sample spinning NMR studies of macromolecules and ordered systems"]}]}],"canonical_facts":{"dc:contributor":["Oldfield, Eric"],"dc:creator":["Chung, John"],"dc:date":["2011-05-07T13:43:11Z","10000-01-01","1991"],"dc:description":["\"We have studied a variety of macromolecular systems such as lipid/water lyotropic phases and elastomeric polymers, and in addition a thermotropic liquid-crystal displaying macroscopic orientational ordering behavior, by Carbon-13 ($\\sp{13}$C) nuclear magnetic resonance (NMR) spectroscopy. We find that under \"\"magic angle\"\" spinning (MAS) these systems display high resolution due to extensive motions, and therefore traditional proton-decoupling is not necessary. In the absence of proton decoupling, i.e., proton-coupled MAS (PCMAS), we find that these systems display scalar hyperfine-coupled $\\sp{13}$C splittings with radically asymmetric linewidths and shapes. We attribute these effects to cross-correlation terms between two or more different relaxation mechanisms, (dipolar/chemical shift anisotropy (DD/CSA) relaxations) at the high magnetic fields employed.\"","Since the DD/CSA effects are quite novel and have not been treated in detail experimentally or theoretically, we have extended the previous theories to a more realistic anisotropic motional model and have attempted to explain the proton-coupled $\\sp{13}$C longitudinal relaxation data in two elastomers by fitting it to the simple model. The data does not explain the model in an intuitively reasonable fashion; and it is concluded that more work needs to be done in order to study a system with more experimental measurables which would allow for fitting to a more elaborate theory of restricted motions.","\"We have also tried to extend the usefulness of PC-MAS relaxation cross-correlation study to a thermotropic liquid crystal; and in the process we have determined the effects which sample spinning in a magnetic field can have on an ordered phase such as the nematic phase of a liquid crystal. Our findings indicate that rapid spinning of the sample can lead to destruction of the macroscopic order-director alignment along the sample spinner axis. In order to avoid this difficulty \"\"off-axis\"\" spinning experiments are done to show that the stability of the order director can be maintained. With the added precaution we show that proton-coupled $\\sp{13}$C relaxation study is feasible in the nematic phase; and from the measured relaxation time constants we obtain macroscopic cross-correlation spectral densities, although the interpretation of these spectral densities is dependent on the of knowledge of the accurate static tensor elements.\"","Made available in DSpace on 2011-05-07T13:43:11Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9210769.pdf: 3993379 bytes, checksum: 8760939145d3218d6373cbbbb36427c9 (MD5) Previous issue date: 1991","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:58:19Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:27:25-05:00 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"],"dc:identifier":["AAI9210769","(UMI)AAI9210769","http://hdl.handle.net/2142/22541"],"dc:language":["eng"],"dc:rights":["Copyright 1991 Chung, John"],"dc:subject":["Chemistry, Physical"],"dc:title":["Proton-coupled carbon-13 sample spinning NMR studies of macromolecules and ordered systems"],"dc:type":["text"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:20Z"}