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You searched for +publisher:"University of North Carolina" +contributor:("Giokas, Paul"). One record found.

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University of North Carolina

1. Giokas, Paul. Investigating Molecule-Semiconductor Interfaces with Nonlinear Spectroscopies.

Degree: Chemistry, 2016, University of North Carolina

Knowledge of electronic structures and transport mechanisms at molecule-semiconductor interfaces is motivated by their ubiquity in photoelectrochemical cells. In this dissertation, optical spectroscopies are used uncover the influence of electronic coupling, coherent vibrational motion, and molecular geometry, and other factors on dynamics initiated by light absorption at such interfaces. These are explored for a family of ruthenium bipyridyl chromophores bound to titanium dioxide. Transient absorption measurements show molecular singlet state electron injection in 100 fs or less. Resonance Raman intensity analysis suggests the electronic excitations possess very little charge transfer character. The connections drawn in this work between molecular structure and photophysical behavior contribute to the general understanding of photoelectrochemical cells. Knowledge of binding geometry in nanocrystalline films is challenged by heterogeneity of semiconductor surfaces. Polarized resonance Raman spectroscopy is used to characterize the ruthenium chromophore family on single crystal titanium dioxide . Chromophores display a broad distribution of molecular geometries at the interface, with increased variation in binding angle due to the presence of a methylene bridge, as well as additional phosphonate anchors. This result implies multiple binding configurations for chromophores which incorporate multiple phosphonate ligands, and indicates the need for careful consideration when developing surface-assembled chromophore-catalyst cells. Electron transfer transitions occurring on the 100 fs time scale challenge conventional second-order approximations made when modeling these reactions. A fourth-order perturbative model which includes the relationship between coincident electron transfer and nuclear relaxation processes is presented. Insights provided by the model are illustrated for a two-level donor molecule. The presented fourth-order rate formula constitutes a rigorous and intuitive framework for understanding sub-picosecond photoinduced electron transfer dynamics. Charge transfer systems fit by this model include catechol-sensitized titanium dioxide nanoparticles and a closely-related molecular complex. These systems exhibit vibrational coherence coincident with back-electron transfer in the first picosecond after excitation, which suggests that intramolecular nuclear motion strongly influences the electronic transfer process and plays an important role in the dynamics of interfacial systems following light absorption. Advisors/Committee Members: Giokas, Paul, Moran, Andrew, Kanai, Yosuke, Brennaman, Matthew, You, Wei, Atkin, Joanna.

Subjects/Keywords: College of Arts and Sciences; Department of Chemistry

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Giokas, P. (2016). Investigating Molecule-Semiconductor Interfaces with Nonlinear Spectroscopies. (Thesis). University of North Carolina. Retrieved from https://cdr.lib.unc.edu/record/uuid:b42aa3ea-f45f-4a69-bb1c-406f228f2f4d

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Giokas, Paul. “Investigating Molecule-Semiconductor Interfaces with Nonlinear Spectroscopies.” 2016. Thesis, University of North Carolina. Accessed November 28, 2020. https://cdr.lib.unc.edu/record/uuid:b42aa3ea-f45f-4a69-bb1c-406f228f2f4d.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Giokas, Paul. “Investigating Molecule-Semiconductor Interfaces with Nonlinear Spectroscopies.” 2016. Web. 28 Nov 2020.

Vancouver:

Giokas P. Investigating Molecule-Semiconductor Interfaces with Nonlinear Spectroscopies. [Internet] [Thesis]. University of North Carolina; 2016. [cited 2020 Nov 28]. Available from: https://cdr.lib.unc.edu/record/uuid:b42aa3ea-f45f-4a69-bb1c-406f228f2f4d.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Giokas P. Investigating Molecule-Semiconductor Interfaces with Nonlinear Spectroscopies. [Thesis]. University of North Carolina; 2016. Available from: https://cdr.lib.unc.edu/record/uuid:b42aa3ea-f45f-4a69-bb1c-406f228f2f4d

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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