{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/25736"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/25736","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Spin-lattice relaxation of trivalent praseodymium, terbium, and erbium in anhydrous lanthanum trichloride: Temperature and magnetic field dependence","abstract":"We present the results of our measurements of the spinlattice relaxation rates of several trivalent rare earth ions, in the temperature range 0.25 - 4.2o K. We analyze these results within the framework of the Kronig-Van Vleck-Orbach theory, the main features of which we derive in a semi-rigorous manner. We used the pulse saturation method, operating at a microwave frequency of 15.5 GHz. Through additional measurements of our own and of others on the same samples at 9 GHz, we were able to check the frequency (or field) dependence of the relaxation rates. The non-Kramers Pr:LaC13 system was bottlenecked in the direct region and hence its relaxation rate was essentially frequency independent. The Kramers system Er:LaC13 showed a direct process frequency dependence which was very close to the fourth power law of Van Vleck; the non-Kramers system Tb:LaC13 had a direct relaxation process which varied with the square of the frequency, a variation close to that predicted. Actually, the Tb:LaC13. system is somewhat unusual in that a crystal field splitting of its ground doublet results in the composition of its two lowest states being a function of the magnitude of the applied field. This situation should result in a fairly strong field dependence for the Raman and Orbach coefficients, a dependence which is observed experimentally. In contrast, no frequency dependence was expected or observed for the Raman and Orbach coefficients for Er:LaC13 , The low temperatures used in these experiments were attained through the use of a helium-three cryostat. The construction of this cryostat and the associated ESR pulse spectrometer are described in some detail.","abstract_html":"We present the results of our measurements of the spinlattice relaxation rates of several trivalent rare earth ions, in the temperature range 0.25 - 4.2o K. We analyze these results within the framework of the Kronig-Van Vleck-Orbach theory, the main features of which we derive in a semi-rigorous manner. We used the pulse saturation method, operating at a microwave frequency of 15.5 GHz. Through additional measurements of our own and of others on the same samples at 9 GHz, we were able to check the frequency (or field) dependence of the relaxation rates. The non-Kramers Pr:LaC13 system was bottlenecked in the direct region and hence its relaxation rate was essentially frequency independent. The Kramers system Er:LaC13 showed a direct process frequency dependence which was very close to the fourth power law of Van Vleck; the non-Kramers system Tb:LaC13 had a direct relaxation process which varied with the square of the frequency, a variation close to that predicted. Actually, the Tb:LaC13. system is somewhat unusual in that a crystal field splitting of its ground doublet results in the composition of its two lowest states being a function of the magnitude of the applied field. This situation should result in a fairly strong field dependence for the Raman and Orbach coefficients, a dependence which is observed experimentally. In contrast, no frequency dependence was expected or observed for the Raman and Orbach coefficients for Er:LaC13 , The low temperatures used in these experiments were attained through the use of a helium-three cryostat. The construction of this cryostat and the associated ESR pulse spectrometer are described in some detail.","abstract_has_math":false,"creators":["Bohan, Thomas Lynch"],"institution":null,"degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Stapleton, H.J."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-07-08T18:40:42Z","date_published":"2011-07-08T18:40:42Z","updated_at":"2026-07-22T22:25:26Z","subjects":["spin-lattice relaxation","trivalent praseodymium","terbium","erbium","anhydrous lanthanum trichloride"],"languages":["en"],"rights":["1968 Thomas Lynch Bohan"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["6082710"],"render_values":[{"text":"6082710","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/25736","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Stapleton, H.J."]},{"key":"dc:creator","label":"Author","values":["Bohan, Thomas Lynch"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-07-08T18:40:42Z","10000-01-01","1968"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation / Thesis","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."]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["spin-lattice relaxation","trivalent praseodymium","terbium","erbium","anhydrous lanthanum trichloride"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["1968 Thomas Lynch Bohan"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["6082710","http://hdl.handle.net/2142/25736"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["We present the results of our measurements of the spinlattice relaxation rates of several trivalent rare earth ions, in the temperature range 0.25 - 4.2o K. We analyze these results within the framework of the Kronig-Van Vleck-Orbach theory, the main features of which we derive in a semi-rigorous manner. We used the pulse saturation method, operating at a microwave frequency of 15.5 GHz. Through additional measurements of our own and of others on the same samples at 9 GHz, we were able to check the frequency (or field) dependence of the relaxation rates. The non-Kramers Pr:LaC13 system was bottlenecked in the direct region and hence its relaxation rate was essentially frequency independent. The Kramers system Er:LaC13 showed a direct process frequency dependence which was very close to the fourth power law of Van Vleck; the non-Kramers system Tb:LaC13 had a direct relaxation process which varied with the square of the frequency, a variation close to that predicted. Actually, the Tb:LaC13. system is somewhat unusual in that a crystal field splitting of its ground doublet results in the composition of its two lowest states being a function of the magnitude of the applied field. This situation should result in a fairly strong field dependence for the Raman and Orbach coefficients, a dependence which is observed experimentally. In contrast, no frequency dependence was expected or observed for the Raman and Orbach coefficients for Er:LaC13 , The low temperatures used in these experiments were attained through the use of a helium-three cryostat. The construction of this cryostat and the associated ESR pulse spectrometer are described in some detail.","Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-07-08T18:40:42Z No. of bitstreams: 1 1968_bohan.pdf: 5058133 bytes, checksum: b47e7faecf6a64a92d258390ae725552 (MD5)","Made available in DSpace on 2011-07-08T18:40:42Z (GMT). No. of bitstreams: 1 1968_bohan.pdf: 5058133 bytes, checksum: b47e7faecf6a64a92d258390ae725552 (MD5) Previous issue date: 1968","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-07-08T18:40:42Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:33:06-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis","Thesis","U of I Only"]},{"key":"dc:title","label":"Title","values":["Spin-lattice relaxation of trivalent praseodymium, terbium, and erbium in anhydrous lanthanum trichloride: Temperature and magnetic field dependence"]}]}],"canonical_facts":{"dc:contributor":["Stapleton, H.J."],"dc:creator":["Bohan, Thomas Lynch"],"dc:date":["2011-07-08T18:40:42Z","10000-01-01","1968"],"dc:description":["We present the results of our measurements of the spinlattice relaxation rates of several trivalent rare earth ions, in the temperature range 0.25 - 4.2o K. We analyze these results within the framework of the Kronig-Van Vleck-Orbach theory, the main features of which we derive in a semi-rigorous manner. We used the pulse saturation method, operating at a microwave frequency of 15.5 GHz. Through additional measurements of our own and of others on the same samples at 9 GHz, we were able to check the frequency (or field) dependence of the relaxation rates. The non-Kramers Pr:LaC13 system was bottlenecked in the direct region and hence its relaxation rate was essentially frequency independent. The Kramers system Er:LaC13 showed a direct process frequency dependence which was very close to the fourth power law of Van Vleck; the non-Kramers system Tb:LaC13 had a direct relaxation process which varied with the square of the frequency, a variation close to that predicted. Actually, the Tb:LaC13. system is somewhat unusual in that a crystal field splitting of its ground doublet results in the composition of its two lowest states being a function of the magnitude of the applied field. This situation should result in a fairly strong field dependence for the Raman and Orbach coefficients, a dependence which is observed experimentally. In contrast, no frequency dependence was expected or observed for the Raman and Orbach coefficients for Er:LaC13 , The low temperatures used in these experiments were attained through the use of a helium-three cryostat. The construction of this cryostat and the associated ESR pulse spectrometer are described in some detail.","Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-07-08T18:40:42Z No. of bitstreams: 1 1968_bohan.pdf: 5058133 bytes, checksum: b47e7faecf6a64a92d258390ae725552 (MD5)","Made available in DSpace on 2011-07-08T18:40:42Z (GMT). No. of bitstreams: 1 1968_bohan.pdf: 5058133 bytes, checksum: b47e7faecf6a64a92d258390ae725552 (MD5) Previous issue date: 1968","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-07-08T18:40:42Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:33:06-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis","Thesis","U of I Only"],"dc:identifier":["6082710","http://hdl.handle.net/2142/25736"],"dc:language":["en"],"dc:rights":["1968 Thomas Lynch Bohan"],"dc:subject":["spin-lattice relaxation","trivalent praseodymium","terbium","erbium","anhydrous lanthanum trichloride"],"dc:title":["Spin-lattice relaxation of trivalent praseodymium, terbium, and erbium in anhydrous lanthanum trichloride: Temperature and magnetic field dependence"],"dc:type":["Dissertation / Thesis","text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."]},"updated_at":"2026-07-22T22:25:26Z"}