{"id":{"repo_id":"vcu","oai_identifier":"oai:scholarscompass.vcu.edu:etd-1968"},"canonical_url":"https://search.dev.ndltd.org/etd/vcu/oai:scholarscompass.vcu.edu:etd-1968","repository":{"repo_id":"vcu","name":"Virginia Commonwealth University","base_url":"https://scholarscompass.vcu.edu/do/oai/"},"display":{"title":"Enhancing the Third-Order Nonlinear Optical Properties of Porphyrins and Molecular Wires","abstract":"The third-order nonlinear optical (NLO) properties of indium tin oxide (ITO) thin films, Fe3+, Mn3+, Co2+ 5,10,15,20-tetrakis-4hydroxytetraphenyl)porphyrin (TPP) films, and a series of ethynyl-linked azobenzene oligomers were investigated using degenerate four wave mixing (DFWM) with 100 fs laser pulses. To measure the NLO of ITO thin films, A DFWM method for measuring thin films on thick substrates was refined for the characterization of films less than 100 nm thick and applied to ITO films ~25 nm thick. It was found that the third-order nonlinear susceptibility of ITO, χ(3)ITO, is purely electronic at 900 - 1300 nm (11000 - 7700 cm-1) and has a value of (2.16 ± 0.18) x 10-l8 m2 V-2. The χ(3)IT0 value reaches (3.36 ± 0.28) x 10-l8 m2 V(sup>-2 at 1500 nm (6700 cm-1) due to two-photon absorption by free carriers (electrons). Ultrafast electron relaxation was also observed. The ~100 fs lifetime of this process could reflect electron scattering in the conduction band. This DFWM method was also used to investigate the two-photon properties of ~500 nm thick electropolymerized films of Fe3+, Mn3+, and Co2+ TPP in the near-IR spectral region. Metalloporphyrins with strong charge transfer (CT) transitions inthe linear absorption spectra also show enhanced two-photon absorption. (Metalloporphyrin two-photon absorption cross section, δ, increases >10 times over that for the metal free porphyrin.) This effect was attributed to a two-photon induced charge transfer between the metal ion's d orbitals and the π-system of the porphyrin. Correlationof one- and two-photon absorption properties of transition metal porphyrins suggests a new and simple approach to improve organic materials for photonic applications. Finally, a series of oligomers consisting of ethynyl-linked azobenzene units was prepared using Pd-catalyzed cross coupling. The linear and nonlinear optical properties of the oligomers were investigated. The molecular second hyperpolarizability, γ, followed the power law γσ n2.12±0.05 (n is number of repeat units) for unusually large molecular lengths. The exceptional exciton delocalization length exceeds 360 conjugated bonds (>49 nm) and is attributed to the rigidity of the conjugated backbone.","abstract_html":"The third-order nonlinear optical (NLO) properties of indium tin oxide (ITO) thin films, Fe3+, Mn3+, Co2+ 5,10,15,20-tetrakis-4hydroxytetraphenyl)porphyrin (TPP) films, and a series of ethynyl-linked azobenzene oligomers were investigated using degenerate four wave mixing (DFWM) with 100 fs laser pulses. To measure the NLO of ITO thin films, A DFWM method for measuring thin films on thick substrates was refined for the characterization of films less than 100 nm thick and applied to ITO films ~25 nm thick. It was found that the third-order nonlinear susceptibility of ITO, χ(3)ITO, is purely electronic at 900 - 1300 nm (11000 - 7700 cm-1) and has a value of (2.16 ± 0.18) x 10-l8 m2 V-2. The χ(3)IT0 value reaches (3.36 ± 0.28) x 10-l8 m2 V(sup>-2 at 1500 nm (6700 cm-1) due to two-photon absorption by free carriers (electrons). Ultrafast electron relaxation was also observed. The ~100 fs lifetime of this process could reflect electron scattering in the conduction band. This DFWM method was also used to investigate the two-photon properties of ~500 nm thick electropolymerized films of Fe3+, Mn3+, and Co2+ TPP in the near-IR spectral region. Metalloporphyrins with strong charge transfer (CT) transitions inthe linear absorption spectra also show enhanced two-photon absorption. (Metalloporphyrin two-photon absorption cross section, δ, increases >10 times over that for the metal free porphyrin.) This effect was attributed to a two-photon induced charge transfer between the metal ion's d orbitals and the π-system of the porphyrin. Correlationof one- and two-photon absorption properties of transition metal porphyrins suggests a new and simple approach to improve organic materials for photonic applications. Finally, a series of oligomers consisting of ethynyl-linked azobenzene units was prepared using Pd-catalyzed cross coupling. The linear and nonlinear optical properties of the oligomers were investigated. The molecular second hyperpolarizability, γ, followed the power law γσ n2.12±0.05 (n is number of repeat units) for unusually large molecular lengths. The exceptional exciton delocalization length exceeds 360 conjugated bonds (>49 nm) and is attributed to the rigidity of the conjugated backbone.","abstract_has_math":false,"creators":["Humphrey, Jonathan L."],"institution":null,"degree_name":"Doctor of Philosophy","degree_level":"Dissertation","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":["Dr. Darius Kuciauskas"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2006,"date_issued":"2006-01-01T08:00:00Z","date_published":"2006-01-01T08:00:00Z","updated_at":"2026-07-24T05:54:40Z","subjects":["nonlinear optics","laser","degenerate four wave mixing","porphyrin","Chemistry","Physical Sciences and Mathematics"],"languages":[],"rights":["© The Author"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarscompass.vcu.edu/etd/969"],"render_values":[{"text":"https://scholarscompass.vcu.edu/etd/969","href":"https://scholarscompass.vcu.edu/etd/969","code":true}]}]},"links":{"outbound_url":"https://doi.org/10.25772/09EW-DV65","outbound_label":"DOI","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. Darius Kuciauskas"]},{"key":"dc:creator","label":"Author","values":["Humphrey, Jonathan L."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2014-07-09T07:00:00Z"]},{"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":["Doctor of Philosophy"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["nonlinear optics","laser","degenerate four wave mixing","porphyrin","Chemistry","Physical Sciences and Mathematics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["© The Author"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://doi.org/10.25772/09EW-DV65","https://scholarscompass.vcu.edu/etd/969"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The third-order nonlinear optical (NLO) properties of indium tin oxide (ITO) thin films, Fe3+, Mn3+, Co2+ 5,10,15,20-tetrakis-4hydroxytetraphenyl)porphyrin (TPP) films, and a series of ethynyl-linked azobenzene oligomers were investigated using degenerate four wave mixing (DFWM) with 100 fs laser pulses. To measure the NLO of ITO thin films, A DFWM method for measuring thin films on thick substrates was refined for the characterization of films less than 100 nm thick and applied to ITO films ~25 nm thick. It was found that the third-order nonlinear susceptibility of ITO, χ(3)ITO, is purely electronic at 900 - 1300 nm (11000 - 7700 cm-1) and has a value of (2.16 ± 0.18) x 10-l8 m2 V-2. The χ(3)IT0 value reaches (3.36 ± 0.28) x 10-l8 m2 V(sup>-2 at 1500 nm (6700 cm-1) due to two-photon absorption by free carriers (electrons). Ultrafast electron relaxation was also observed. The ~100 fs lifetime of this process could reflect electron scattering in the conduction band. This DFWM method was also used to investigate the two-photon properties of ~500 nm thick electropolymerized films of Fe3+, Mn3+, and Co2+ TPP in the near-IR spectral region. Metalloporphyrins with strong charge transfer (CT) transitions inthe linear absorption spectra also show enhanced two-photon absorption. (Metalloporphyrin two-photon absorption cross section, δ, increases >10 times over that for the metal free porphyrin.) This effect was attributed to a two-photon induced charge transfer between the metal ion's d orbitals and the π-system of the porphyrin. Correlationof one- and two-photon absorption properties of transition metal porphyrins suggests a new and simple approach to improve organic materials for photonic applications. Finally, a series of oligomers consisting of ethynyl-linked azobenzene units was prepared using Pd-catalyzed cross coupling. The linear and nonlinear optical properties of the oligomers were investigated. The molecular second hyperpolarizability, γ, followed the power law γσ n2.12±0.05 (n is number of repeat units) for unusually large molecular lengths. The exceptional exciton delocalization length exceeds 360 conjugated bonds (>49 nm) and is attributed to the rigidity of the conjugated backbone."]},{"key":"dc:title","label":"Title","values":["Enhancing the Third-Order Nonlinear Optical Properties of Porphyrins and Molecular Wires"]}]}],"canonical_facts":{"dc:contributor":["Dr. Darius Kuciauskas"],"dc:creator":["Humphrey, Jonathan L."],"dc:date.available":["2014-07-09T07:00:00Z"],"dc:description.abstract":["The third-order nonlinear optical (NLO) properties of indium tin oxide (ITO) thin films, Fe3+, Mn3+, Co2+ 5,10,15,20-tetrakis-4hydroxytetraphenyl)porphyrin (TPP) films, and a series of ethynyl-linked azobenzene oligomers were investigated using degenerate four wave mixing (DFWM) with 100 fs laser pulses. To measure the NLO of ITO thin films, A DFWM method for measuring thin films on thick substrates was refined for the characterization of films less than 100 nm thick and applied to ITO films ~25 nm thick. It was found that the third-order nonlinear susceptibility of ITO, χ(3)ITO, is purely electronic at 900 - 1300 nm (11000 - 7700 cm-1) and has a value of (2.16 ± 0.18) x 10-l8 m2 V-2. The χ(3)IT0 value reaches (3.36 ± 0.28) x 10-l8 m2 V(sup>-2 at 1500 nm (6700 cm-1) due to two-photon absorption by free carriers (electrons). Ultrafast electron relaxation was also observed. The ~100 fs lifetime of this process could reflect electron scattering in the conduction band. This DFWM method was also used to investigate the two-photon properties of ~500 nm thick electropolymerized films of Fe3+, Mn3+, and Co2+ TPP in the near-IR spectral region. Metalloporphyrins with strong charge transfer (CT) transitions inthe linear absorption spectra also show enhanced two-photon absorption. (Metalloporphyrin two-photon absorption cross section, δ, increases >10 times over that for the metal free porphyrin.) This effect was attributed to a two-photon induced charge transfer between the metal ion's d orbitals and the π-system of the porphyrin. Correlationof one- and two-photon absorption properties of transition metal porphyrins suggests a new and simple approach to improve organic materials for photonic applications. Finally, a series of oligomers consisting of ethynyl-linked azobenzene units was prepared using Pd-catalyzed cross coupling. The linear and nonlinear optical properties of the oligomers were investigated. The molecular second hyperpolarizability, γ, followed the power law γσ n2.12±0.05 (n is number of repeat units) for unusually large molecular lengths. The exceptional exciton delocalization length exceeds 360 conjugated bonds (>49 nm) and is attributed to the rigidity of the conjugated backbone."],"dc:identifier":["https://doi.org/10.25772/09EW-DV65","https://scholarscompass.vcu.edu/etd/969"],"dc:rights":["© The Author"],"dc:subject":["nonlinear optics","laser","degenerate four wave mixing","porphyrin","Chemistry","Physical Sciences and Mathematics"],"dc:title":["Enhancing the Third-Order Nonlinear Optical Properties of Porphyrins and Molecular Wires"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy"]},"updated_at":"2026-07-24T05:54:40Z"}