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dc.contributor.authorGuo, Fangyeong.
dc.creatorGuo, Fangyeong.en_US
dc.date.accessioned2011-10-31T18:17:16Z
dc.date.available2011-10-31T18:17:16Z
dc.date.issued1994en_US
dc.identifier.urihttp://hdl.handle.net/10150/186708
dc.description.abstractWithin the framework of the extended-Hubbard model, theoretical studies on the intensities of two-photon absorption (TPA) of the even-parity states in conjugated polymers show relatively large contributions from the exciton mA(g) state. The TPA intensities due to the 2A(g) as well as other sub-gap even-parity states are demonstrated to be extremely weak in the long chain limit, independent of their locations relative to the optically allowed exciton. We show our results have important implications for the interpretation of third harmonic generation (THG) and TPA spectra of several conjugated polymers. We have also probed the higher energy states that are reached by two-electron excitations from the ground state. Evidence for the biexciton, a bound state of two excitons that occurs below the two-electron continuum, is found. The lowest biexciton state is of even parity, call be reached by optical excitation from the 1Bᵤ exciton, and also by two-photon excitation from the ground state. Interpretation of a recent picosecond photoinduced absorption experiment on polyparavinylene (PPV) and TPA on polysilanes (PS) in terms of the biexciton will be given. Multiexciton states have experimentally found in a linear chain mixed-stack charge-transfer solid. Our theoretical studies based on the extended-Hubbard Hamiltonian demonstrate that such stable multiexciton states in this class of organic systems are due to the Coulomb interactions.
dc.language.isoenen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.titleHigh energy excited states in conjugated polymers and charge-transfer solids.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.contributor.chairMazumdar, Sumitendraen_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.contributor.committeememberLeavitt, J. A.en_US
dc.contributor.committeememberStein, D.en_US
dc.contributor.committeememberStark, R.en_US
dc.contributor.committeememberVuillemin, J.en_US
dc.identifier.proquest9426338en_US
thesis.degree.disciplinePhysicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.namePh.D.en_US
refterms.dateFOA2018-04-26T13:12:02Z
html.description.abstractWithin the framework of the extended-Hubbard model, theoretical studies on the intensities of two-photon absorption (TPA) of the even-parity states in conjugated polymers show relatively large contributions from the exciton mA(g) state. The TPA intensities due to the 2A(g) as well as other sub-gap even-parity states are demonstrated to be extremely weak in the long chain limit, independent of their locations relative to the optically allowed exciton. We show our results have important implications for the interpretation of third harmonic generation (THG) and TPA spectra of several conjugated polymers. We have also probed the higher energy states that are reached by two-electron excitations from the ground state. Evidence for the biexciton, a bound state of two excitons that occurs below the two-electron continuum, is found. The lowest biexciton state is of even parity, call be reached by optical excitation from the 1Bᵤ exciton, and also by two-photon excitation from the ground state. Interpretation of a recent picosecond photoinduced absorption experiment on polyparavinylene (PPV) and TPA on polysilanes (PS) in terms of the biexciton will be given. Multiexciton states have experimentally found in a linear chain mixed-stack charge-transfer solid. Our theoretical studies based on the extended-Hubbard Hamiltonian demonstrate that such stable multiexciton states in this class of organic systems are due to the Coulomb interactions.


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