{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/46646"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/46646","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Spectroscopic signatures of doorway-mediated intersystem crossing","abstract":"Intersystem crossing in acetylene, C₂H₂, is described by a doorway-mediated model, where singlet-triplet mixing between the first excited singlet~ state, S₁, and the manifold of low-lying T₁,₂ states is controlled by special vibrational levels of the third excited triplet state, T₃. However, the influence of T₃ doorway states on the ~A¹Au <-- ~X¹[sigma]+g spectrum of acetylene is not well characterized for most S₁ vibrational levels. The doorway model is formulated to account for the LIF/SEELEM spectra of S₁ vibrational sublevels that are weakly perturbed by T₃ doorway states. The structure and properties of a doorway-mediated effective Hamiltonian are discussed, and a method for spectral deconvolution is presented for the doorway model. The dependence of fluorescence center-of-gravity on the time delay of a gated integration region is developed as an analysis tool for LIF spectroscopy. Triplet perturbations in the spectra of four S₁ vibrational sublevels are discussed in terms of the doorway model, using this new tool. IR-UV double resonance LIF/SEELEM spectroscopy is used to investigate the role of the torsional and \"cis\"-bending vibrational modes of S₁ in the promotion of vibrational overlap between levels of S₁ and T₃. A collisional method for the population of metastable molecules in a pulsed supersonic expansion is presented and discussed.","abstract_html":"Intersystem crossing in acetylene, C₂H₂, is described by a doorway-mediated model, where singlet-triplet mixing between the first excited singlet~ state, S₁, and the manifold of low-lying T₁,₂ states is controlled by special vibrational levels of the third excited triplet state, T₃. However, the influence of T₃ doorway states on the ~A¹Au &lt;-- ~X¹[sigma]+g spectrum of acetylene is not well characterized for most S₁ vibrational levels. The doorway model is formulated to account for the LIF/SEELEM spectra of S₁ vibrational sublevels that are weakly perturbed by T₃ doorway states. The structure and properties of a doorway-mediated effective Hamiltonian are discussed, and a method for spectral deconvolution is presented for the doorway model. The dependence of fluorescence center-of-gravity on the time delay of a gated integration region is developed as an analysis tool for LIF spectroscopy. Triplet perturbations in the spectra of four S₁ vibrational sublevels are discussed in terms of the doorway model, using this new tool. IR-UV double resonance LIF/SEELEM spectroscopy is used to investigate the role of the torsional and &quot;cis&quot;-bending vibrational modes of S₁ in the promotion of vibrational overlap between levels of S₁ and T₃. A collisional method for the population of metastable molecules in a pulsed supersonic expansion is presented and discussed.","abstract_has_math":false,"creators":["Bittinger, Kyle Lee"],"institution":"Massachusetts Institute of Technology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Dept. of Chemistry.","school":null,"contributors":[],"advisors":["Robert W. Field."],"committee_chairs":[],"committee_members":[],"year":2009,"date_issued":"2009","date_published":"2009","updated_at":"2026-07-22T22:22:14Z","subjects":["Chemistry."],"languages":["eng"],"rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"rights_urls":["http://dspace.mit.edu/handle/1721.1/7582"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1721.1/46646","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Robert W. Field."]},{"key":"dc:contributor.department","label":"Department","values":["Massachusetts Institute of Technology. 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Dept. of Chemistry."]},{"key":"dc:creator","label":"Author","values":["Bittinger, Kyle Lee"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2009-08-26T17:11:42Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2009-08-26T17:11:42Z"]},{"key":"dc:date.issued","label":"Date","values":["2009"]},{"key":"dc:publisher","label":"Institution","values":["Massachusetts Institute of Technology"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Chemistry."]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://dspace.mit.edu/handle/1721.1/7582"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1721.1/46646"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2009.","Vita.","Includes bibliographical references (p. 229-239)."]},{"key":"dc:description.abstract","label":"Abstract","values":["Intersystem crossing in acetylene, C₂H₂, is described by a doorway-mediated model, where singlet-triplet mixing between the first excited singlet~ state, S₁, and the manifold of low-lying T₁,₂ states is controlled by special vibrational levels of the third excited triplet state, T₃. However, the influence of T₃ doorway states on the ~A¹Au <-- ~X¹[sigma]+g spectrum of acetylene is not well characterized for most S₁ vibrational levels. The doorway model is formulated to account for the LIF/SEELEM spectra of S₁ vibrational sublevels that are weakly perturbed by T₃ doorway states. The structure and properties of a doorway-mediated effective Hamiltonian are discussed, and a method for spectral deconvolution is presented for the doorway model. The dependence of fluorescence center-of-gravity on the time delay of a gated integration region is developed as an analysis tool for LIF spectroscopy. Triplet perturbations in the spectra of four S₁ vibrational sublevels are discussed in terms of the doorway model, using this new tool. IR-UV double resonance LIF/SEELEM spectroscopy is used to investigate the role of the torsional and \"cis\"-bending vibrational modes of S₁ in the promotion of vibrational overlap between levels of S₁ and T₃. A collisional method for the population of metastable molecules in a pulsed supersonic expansion is presented and discussed."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph.D."]},{"key":"dc:title","label":"Title","values":["Spectroscopic signatures of doorway-mediated intersystem crossing"]}]}],"canonical_facts":{"dc:contributor.advisor":["Robert W. Field."],"dc:contributor.department":["Massachusetts Institute of Technology. Dept. of Chemistry."],"dc:contributor.other":["Massachusetts Institute of Technology. Dept. of Chemistry."],"dc:creator":["Bittinger, Kyle Lee"],"dc:date.accessioned":["2009-08-26T17:11:42Z"],"dc:date.available":["2009-08-26T17:11:42Z"],"dc:date.issued":["2009"],"dc:description":["Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2009.","Vita.","Includes bibliographical references (p. 229-239)."],"dc:description.abstract":["Intersystem crossing in acetylene, C₂H₂, is described by a doorway-mediated model, where singlet-triplet mixing between the first excited singlet~ state, S₁, and the manifold of low-lying T₁,₂ states is controlled by special vibrational levels of the third excited triplet state, T₃. However, the influence of T₃ doorway states on the ~A¹Au <-- ~X¹[sigma]+g spectrum of acetylene is not well characterized for most S₁ vibrational levels. The doorway model is formulated to account for the LIF/SEELEM spectra of S₁ vibrational sublevels that are weakly perturbed by T₃ doorway states. The structure and properties of a doorway-mediated effective Hamiltonian are discussed, and a method for spectral deconvolution is presented for the doorway model. The dependence of fluorescence center-of-gravity on the time delay of a gated integration region is developed as an analysis tool for LIF spectroscopy. Triplet perturbations in the spectra of four S₁ vibrational sublevels are discussed in terms of the doorway model, using this new tool. IR-UV double resonance LIF/SEELEM spectroscopy is used to investigate the role of the torsional and \"cis\"-bending vibrational modes of S₁ in the promotion of vibrational overlap between levels of S₁ and T₃. A collisional method for the population of metastable molecules in a pulsed supersonic expansion is presented and discussed."],"dc:description.degree":["Ph.D."],"dc:identifier.uri":["http://hdl.handle.net/1721.1/46646"],"dc:language.iso":["eng"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"dc:rights.uri":["http://dspace.mit.edu/handle/1721.1/7582"],"dc:subject":["Chemistry."],"dc:title":["Spectroscopic signatures of doorway-mediated intersystem crossing"],"dc:type":["Thesis"]},"updated_at":"2026-07-22T22:22:14Z"}