+publisher:"University of Colorado" +contributor:("Gordana Dukovic")

University of Colorado

1. Carter, Carly Jo. Bio-mediated Materials: Synthesis, Characterization and Applications.

Degree: PhD, Chemistry & Biochemistry, 2010, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/19

► Biomolecules have evolved in nature with the ability to synthesize materials with uniquely interesting properties in response to environmental stress. Bio-mediated materials are often… (more)

▼ Biomolecules have evolved in nature with the ability to synthesize materials with uniquely interesting properties in response to environmental stress. Bio-mediated materials are often synthesized under conditions of neutral pH and ambient temperature and pressure from a limited set of biologically available metals. This thesis presents work done in an effort to 1) identify biomolecules capable of mediating the synthesis of nanomaterials in vitro, 2) further understand the circumstances that promote bio-mediated materials synthesis and 3) apply the knowledge gained to a novel intracellular protein labeling scheme. In vitro selection experiments involving RNA, phagemids, or whole cells can identify biomolecules that bind tightly to or mediate the formation of inorganic materials. Through this work, iterative cycles of RNA selections have identified RNAs that mediate the formation of metal oxide nanoparticles. The selection pressure required RNA-mediated assembly of Co and/or Fe into a solid that responded to a magnetic field under ambient conditions. The ability of peptides selected via phage display to mediate the formation of inorganic nanoparticles is now well established. However, the atomic-level interactions between the selected peptides and the metal ion precursors remain largely obscure. We identified a new peptide that is capable of mediating the formation of Ag nanoparticles. Surprisingly, nanoparticle formation required the presence of peptide, HEPES buffer, and light. Peptide epitope mapping indicated crucial residues for particle formation. Additionally, once immobilized onto a surface, the peptide formed Ag nanoparticles or high-aspect ratio nanowires as a function of immobilization concentration. Finally, we explored biomolecule-mediated formation of nanomaterials by investigating protein chimeras. We engineered and expressed proteins that included peptides known to bind silver or iron. The Ag and Fe binding peptide-based protein chimeras successfully demonstrated in vitro activity. Additionally the iron binding proteins were capable of scavenging trace iron from Luria-Bertaini broth during protein expression, creating nanoparticles in vivo. These results have lead toward developing genetically clonable tags, where specific proteins are labeled with a biomolecule capable of mediating the synthesis of a nanomaterial, and the unique nanomaterial is used to uniquely identify the protein of interest. Advisors/Committee Members: Daniel L. Feldheim, Bob Sievers, Gordana Dukovic.

Subjects/Keywords: biomediated materials; biomimetic; nanoparticles; silver; Analytical Chemistry; Chemistry; Earth Sciences

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APA (6^th Edition):

Carter, C. J. (2010). Bio-mediated Materials: Synthesis, Characterization and Applications. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/19

Chicago Manual of Style (16^th Edition):

Carter, Carly Jo. “Bio-mediated Materials: Synthesis, Characterization and Applications.” 2010. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/19.

MLA Handbook (7^th Edition):

Carter, Carly Jo. “Bio-mediated Materials: Synthesis, Characterization and Applications.” 2010. Web. 17 Apr 2021.

Vancouver:

Carter CJ. Bio-mediated Materials: Synthesis, Characterization and Applications. [Internet] [Doctoral dissertation]. University of Colorado; 2010. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/19.

Council of Science Editors:

Carter CJ. Bio-mediated Materials: Synthesis, Characterization and Applications. [Doctoral Dissertation]. University of Colorado; 2010. Available from: https://scholar.colorado.edu/chem_gradetds/19

University of Colorado

2. Higgins, Kelsey. Characterization of Gold Nanoparticle Antimicrobials.

Degree: MS, Chemistry & Biochemistry, 2014, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/107

► Nanoparticles have been gaining recognition for their potential in drug delivery; however, now a new niche is growing. Nanoparticles are no longer simply carrying… (more)

Subjects/Keywords: charaterization; e. coli; gold nanoparticle; hplc; Biochemistry; Medicinal-Pharmaceutical Chemistry

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APA (6^th Edition):

Higgins, K. (2014). Characterization of Gold Nanoparticle Antimicrobials. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/107

Chicago Manual of Style (16^th Edition):

Higgins, Kelsey. “Characterization of Gold Nanoparticle Antimicrobials.” 2014. Masters Thesis, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/107.

MLA Handbook (7^th Edition):

Higgins, Kelsey. “Characterization of Gold Nanoparticle Antimicrobials.” 2014. Web. 17 Apr 2021.

Vancouver:

Higgins K. Characterization of Gold Nanoparticle Antimicrobials. [Internet] [Masters thesis]. University of Colorado; 2014. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/107.

Council of Science Editors:

Higgins K. Characterization of Gold Nanoparticle Antimicrobials. [Masters Thesis]. University of Colorado; 2014. Available from: https://scholar.colorado.edu/chem_gradetds/107

University of Colorado

3. Zhang, Jing. The Mechanism of Thermally-Activated Photoluminescence Quenching and Its Correlation with Transport in Electronically-Coupled PbS Quantum Dot Arrays.

Degree: MS, Chemistry & Biochemistry, 2013, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/145

► We have measured the temperature-dependent photoluminescence (PL) and quantum yield (QY) of a series of alkanedithiol-treated PbS quantum dot (QD) films as a function… (more)

Subjects/Keywords: Band Tail Behavior; Charge Transport; Electronically-Coupled PbS Quantum Dot; PL Quantum Yield; Thermally-Activated Photoluminescence Quenching; Physical Chemistry

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APA (6^th Edition):

Zhang, J. (2013). The Mechanism of Thermally-Activated Photoluminescence Quenching and Its Correlation with Transport in Electronically-Coupled PbS Quantum Dot Arrays. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/145

Chicago Manual of Style (16^th Edition):

Zhang, Jing. “The Mechanism of Thermally-Activated Photoluminescence Quenching and Its Correlation with Transport in Electronically-Coupled PbS Quantum Dot Arrays.” 2013. Masters Thesis, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/145.

MLA Handbook (7^th Edition):

Zhang, Jing. “The Mechanism of Thermally-Activated Photoluminescence Quenching and Its Correlation with Transport in Electronically-Coupled PbS Quantum Dot Arrays.” 2013. Web. 17 Apr 2021.

Vancouver:

Zhang J. The Mechanism of Thermally-Activated Photoluminescence Quenching and Its Correlation with Transport in Electronically-Coupled PbS Quantum Dot Arrays. [Internet] [Masters thesis]. University of Colorado; 2013. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/145.

Council of Science Editors:

Zhang J. The Mechanism of Thermally-Activated Photoluminescence Quenching and Its Correlation with Transport in Electronically-Coupled PbS Quantum Dot Arrays. [Masters Thesis]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/chem_gradetds/145

University of Colorado

4. Hamby, Hayden Tyler. Using Semiconductor Nanocrystals to Drive Redox Enzymes with Light.

Degree: PhD, 2018, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/288

► Nanocrystals are an emergent strategy for providing electrons to redox enzymes for catalysis. In this dissertation I present my work on the investigation of how… (more)

▼ Nanocrystals are an emergent strategy for providing electrons to redox enzymes for catalysis. In this dissertation I present my work on the investigation of how nanocrystals can be used to drive active site chemistry of two different enzymes. In the first project I present for the first time the direct coupling of cadmium sulfide nanorods (CdS NRs) to a CO₂ reduction enzyme for the creation of new carbon-carbon bonds using light. Under optimal conditions, the maximum turnover frequency (TOF_max) for CO₂ reduction is similar to that obtained in the native system where the native electron donor ferredoxin is used; however, high excitation frequencies are needed to reach TOF_max resulting in low quantum yields of 1%. The electron transfer dynamics are investigated as a means to understand this limitation on quantum yield, and we find that the electron transfer rates are dependent on whether the enzyme is bound to reactants. The implications of this new finding are discussed within the context of available crystal structures for the enzyme, and conclusions are drawn about the nature of nanocrystal-protein interactions when the enzymatic catalyst undergoes dynamic conformational changes during light-driven turnover. In the second project I present work performed to promote fast electron transfer in a more well-studied system of CdS NRs and Hydrogenase enzyme (CaI). In this work I substitute an ultrashort, sulfide ligand in place of more conventional 3-mercaptopropionate (MPA) at the interface of the nanocrystal and enzyme to shorten the tunneling barrier to electron transfer. The excited state decay of the CdS-CaI complex is investigated to determine the quantum efficiency of electron transfer (QE_ET). The QE_ET is then compared with light-driven H₂ production to understand the overall impact of ultrashort ligands on the photocatalytic activity. This work concludes with a summary of these important findings and a projection for the future implementation of nanocrystals in photochemical schemes where biological enzymes are used as catalysts. Advisors/Committee Members: Gordana Dukovic, Tanja Cuk, Niels Damrauer, Paul King, Sandeep Sharma.

Subjects/Keywords: artificial photosynthesis; biohybrid systems; catalysis; co2 reduction; nanocrystals; spectroscopy; Nanoscience and Nanotechnology; Physical Chemistry

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APA (6^th Edition):

Hamby, H. T. (2018). Using Semiconductor Nanocrystals to Drive Redox Enzymes with Light. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/288

Chicago Manual of Style (16^th Edition):

Hamby, Hayden Tyler. “Using Semiconductor Nanocrystals to Drive Redox Enzymes with Light.” 2018. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/288.

MLA Handbook (7^th Edition):

Hamby, Hayden Tyler. “Using Semiconductor Nanocrystals to Drive Redox Enzymes with Light.” 2018. Web. 17 Apr 2021.

Vancouver:

Hamby HT. Using Semiconductor Nanocrystals to Drive Redox Enzymes with Light. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/288.

Council of Science Editors:

Hamby HT. Using Semiconductor Nanocrystals to Drive Redox Enzymes with Light. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/chem_gradetds/288

University of Colorado

5. Rossabi, Samuel. Characterization of Volatile Organic Compound Emissions from Anthropogenic and Emerging Biogenic Sources.

Degree: PhD, 2019, University of Colorado

URL: https://scholar.colorado.edu/chemistry_gradetds/8

► Volatile organic compounds are emitted by myriad sources. This thesis investigates trends in emissions on global, regional, and local scales. Globally, an increasing trend… (more)

Subjects/Keywords: bacteria; oil and gas development; soil; trends; volatile organic compounds; Analytical Chemistry; Environmental Chemistry

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APA (6^th Edition):

Rossabi, S. (2019). Characterization of Volatile Organic Compound Emissions from Anthropogenic and Emerging Biogenic Sources. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chemistry_gradetds/8

Chicago Manual of Style (16^th Edition):

Rossabi, Samuel. “Characterization of Volatile Organic Compound Emissions from Anthropogenic and Emerging Biogenic Sources.” 2019. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chemistry_gradetds/8.

MLA Handbook (7^th Edition):

Rossabi, Samuel. “Characterization of Volatile Organic Compound Emissions from Anthropogenic and Emerging Biogenic Sources.” 2019. Web. 17 Apr 2021.

Vancouver:

Rossabi S. Characterization of Volatile Organic Compound Emissions from Anthropogenic and Emerging Biogenic Sources. [Internet] [Doctoral dissertation]. University of Colorado; 2019. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chemistry_gradetds/8.

Council of Science Editors:

Rossabi S. Characterization of Volatile Organic Compound Emissions from Anthropogenic and Emerging Biogenic Sources. [Doctoral Dissertation]. University of Colorado; 2019. Available from: https://scholar.colorado.edu/chemistry_gradetds/8

University of Colorado

6. Abdelhaq, Mirvat. Design, Synthesis a nd Characterization of Ruthenium Polypyridyl Complexes Towards Structural and Conformational Control of Intramolecular Electron Transfer.

Degree: PhD, Chemistry & Biochemistry, 2012, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/62

► The demand for carbon neutral sources of energy has led researchers to turn toward strategies involving conversion of solar photons to produce electricity and… (more)

▼ The demand for carbon neutral sources of energy has led researchers to turn toward strategies involving conversion of solar photons to produce electricity and fuels. Solar conversion is initiated by photoinduced electron transfer (ET) processes. Donor-Bridge-Acceptor (DBA) complexes are a common platform for investigating photoinduced intramolecular electron transfer processes. In this work, two series of DBA complexes have been synthesized and characterized to investigate the role of structural elements on rates of photoinduced intramolecular electron transfer. The DBA complexes are comprised of a ruthenium polypyridyl donor covalently linked to a 4,4'-bipyridinium acceptor by a bridging aryl subunit. We hypothesize that the addition of steric bulk on the donor chromophore and the bridging subunit will alter the lifetimes for forward and back electron transfer processes. New electroactive asymmetric ligands were synthesized in high yields and complexed to produce seven new DBA complexes which were characterized by absorption and emission spectroscopies, cyclic voltammetry and spectroelectrochemistry, electronic structure calculations and picosecond transient absorption techniques. The first series of DBA complexes was prepared to investigate how lifetimes of intramolecular ET are affected by increased methylation on ancillary ligands which is expected to alter driving forces for ET. The electron lifetimes were measured for three complexes that share an electroactive ligand but differ in ancillary ligand. It was determined that the lifetime for forward ET was not significantly altered but the lifetimes for back ET differed by a factor of two. For the second DBA series, methyl groups were systematically introduced onto various positions of the bridging subunit to determine if steric bulk is effective at disrupting electron communication within the complex thereby altering ET lifetimes. Reductive spectroelectrochemistry and transient absorption spectra revealed that steric bulk was effective at localizing electron density onto the acceptor moiety. The measured ET lifetimes showed that the number of methyl substituents on the bridging subunit was more of a determining factor of ET lifetimes than the methyl substituent position. Advisors/Committee Members: Niels H. Damrauer, Gordana Dukovic, Tarek Sammakia, Veronica Bierbaum, Jerry Peterson.

Subjects/Keywords: Chemistry; Physical Chemistry

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APA (6^th Edition):

Abdelhaq, M. (2012). Design, Synthesis a nd Characterization of Ruthenium Polypyridyl Complexes Towards Structural and Conformational Control of Intramolecular Electron Transfer. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/62

Chicago Manual of Style (16^th Edition):

Abdelhaq, Mirvat. “Design, Synthesis a nd Characterization of Ruthenium Polypyridyl Complexes Towards Structural and Conformational Control of Intramolecular Electron Transfer.” 2012. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/62.

MLA Handbook (7^th Edition):

Abdelhaq, Mirvat. “Design, Synthesis a nd Characterization of Ruthenium Polypyridyl Complexes Towards Structural and Conformational Control of Intramolecular Electron Transfer.” 2012. Web. 17 Apr 2021.

Vancouver:

Abdelhaq M. Design, Synthesis a nd Characterization of Ruthenium Polypyridyl Complexes Towards Structural and Conformational Control of Intramolecular Electron Transfer. [Internet] [Doctoral dissertation]. University of Colorado; 2012. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/62.

Council of Science Editors:

Abdelhaq M. Design, Synthesis a nd Characterization of Ruthenium Polypyridyl Complexes Towards Structural and Conformational Control of Intramolecular Electron Transfer. [Doctoral Dissertation]. University of Colorado; 2012. Available from: https://scholar.colorado.edu/chem_gradetds/62

University of Colorado

7. Hewitt, Joshua Thomas. Towards the use of Adaptive Feedback Control Pulse Shaping to Probe and Control Reactivity of the Metal-to-Ligand Charge Transfer Excited State in Ruthenium(II) Bis-Terpyridine Complexes.

Degree: PhD, Chemistry & Biochemistry, 2013, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/77

► A novel ruthenium(II) polypyridyl complex [Ru(bpy-An)(tpy-φ-MV)]4+ (where tpy-An = 4’-(9-anthrcenyl)-2,2’:6’,2’’-terpyridine and tpy-&phi-MV,2+ = 4’-(1-(1’-methyl-4,4-bipyridinium-1-yl)-phenyl)-2,2’:6’,2’’-terpyridine) capable of undergoing energy transfer (EnT) or electron transfer (ET)… (more)

▼ A novel ruthenium(II) polypyridyl complex [Ru(bpy-An)(tpy-φ-MV)]4+ (where tpy-An = 4’-(9-anthrcenyl)-2,2’:6’,2’’-terpyridine and tpy-&phi-MV,2+ = 4’-(1-(1’-methyl-4,4-bipyridinium-1-yl)-phenyl)-2,2’:6’,2’’-terpyridine) capable of undergoing energy transfer (EnT) or electron transfer (ET) following photoexcitation to the metal-to-ligand charge transfer (MLCT) state is investigated. Adaptive feedback control (AFC) pulse shaping, which has proven to be a versatile experimental tool for probing photoinduced dynamics in a variety of chemical systems, is used try and control the EnT and ET reactivity in this complex with the goal of informing the underlying EnT and ET dynamics. To allow for interpretation of the aforementioned AFC experiments the photophysics of [Ru(bpy-An)(tpy-φ-MV)]4+ and a family of six closely related bis-terpyridine Ru(II) complexes are characterized using static absorption, electochemical, and ultrafast pump-probe techniques. These experiments reveal previously unreported dynamics such as equilibration between the 3MLCT and 3MC (where MC = metal centered excited state) and interligand electron transfer. Furthermore, the EnT and ET reactions in [Ru(bpy-An)(tpy-φ-MV)]4+ (and the associated model complexes) are found to occur on a sub-picosecond and picosecond timescale, respectively. These are the fastest EnT and ET timescales reported for any Ru(II) bis-terpyridine based complexes. As an addendum, photophysics of the mononuclear water oxidation catalysts [Ru(bpy)(tpy)(OH₂)]2+ and [Ru(bpy)(tpy)(OD₂)]2+ in neat H₂O and D₂O solvent, respectively, are reported. Ultrafast pump-probe experiments reveal an inverse kinetic isotope effect with the excited state lifetime being shorter for the D₂O complex than the H₂O complex. This is attributed to interactions between the coordinated aqua (or D₂O) and solvent in the MLCT excited state and suggests design principles applicable to synthesis of photo-driven water oxidation assemblies. Advisors/Committee Members: Niels H. Damrauer, Garry Rumbles, Gordana Dukovic, David Jonas, Charles Musgrave.

Subjects/Keywords: Physical Chemistry

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APA (6^th Edition):

Hewitt, J. T. (2013). Towards the use of Adaptive Feedback Control Pulse Shaping to Probe and Control Reactivity of the Metal-to-Ligand Charge Transfer Excited State in Ruthenium(II) Bis-Terpyridine Complexes. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/77

Chicago Manual of Style (16^th Edition):

Hewitt, Joshua Thomas. “Towards the use of Adaptive Feedback Control Pulse Shaping to Probe and Control Reactivity of the Metal-to-Ligand Charge Transfer Excited State in Ruthenium(II) Bis-Terpyridine Complexes.” 2013. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/77.

MLA Handbook (7^th Edition):

Hewitt, Joshua Thomas. “Towards the use of Adaptive Feedback Control Pulse Shaping to Probe and Control Reactivity of the Metal-to-Ligand Charge Transfer Excited State in Ruthenium(II) Bis-Terpyridine Complexes.” 2013. Web. 17 Apr 2021.

Vancouver:

Hewitt JT. Towards the use of Adaptive Feedback Control Pulse Shaping to Probe and Control Reactivity of the Metal-to-Ligand Charge Transfer Excited State in Ruthenium(II) Bis-Terpyridine Complexes. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/77.

Council of Science Editors:

Hewitt JT. Towards the use of Adaptive Feedback Control Pulse Shaping to Probe and Control Reactivity of the Metal-to-Ligand Charge Transfer Excited State in Ruthenium(II) Bis-Terpyridine Complexes. [Doctoral Dissertation]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/chem_gradetds/77

University of Colorado

8. Zhang, Chenxi. Design, Synthesis, and Structure-Property Relationship Study of Shape-Persistent Phenylene Vinylene Macrocycles and Porphyrin-based Molecular Cages through Dynamic Covalent Chemistry.

Degree: PhD, Chemistry & Biochemistry, 2014, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/113

► The objectives of the work described in this thesis are the design and synthesis of shapepersistent phenylene vinylene macrocycles (PVMs) and covalent organic polyhedrons… (more)

▼ The objectives of the work described in this thesis are the design and synthesis of shapepersistent phenylene vinylene macrocycles (PVMs) and covalent organic polyhedrons (COPs) using dynamic covalent chemistry (DC_vC); and the study of their applications in host-guest chemistry, light harvesting, gas adsorption and separation. DC_vC has achieved tremendous progress during the past decade, and its application in constructing complex molecular architectures has attracted increasing attention. Conventional design and preparation of purely organic covalent architectures through irreversible bond formation usually requires multi-step synthesis and is very time consuming and low-yielding. DC_vC exhibits a significant advantage: the reversible nature of the bond formation in DC_vC (“self-correction”-enabled) allows the most thermodynamically stable product to be produced predominantly in one step from readily accessible precursors. DC_vC has been applied in constructing macrocyclic compounds for decades. Moore and coworkers have applied alkyne metathesis in constructing shape-persistent arylene ethynylene macrocycles. Such macrocyclic compounds showed interesting stacking properties for solid-state engineering. Shape-persistent COPs with well-defined intrinsic cavities have been a research focus due to their unique structure features such as customizable geometry and isolated cavities. Moreover, constructed only through robust covalent bonds, the COPs usually have much higher chemical and thermal stability than their supramolecular analogues. Further study beyond COPs involves incorporating COPs into frameworks to construct COFs. In this case, we can have individual well-defined built-in COPs in the frameworks, which are expected to be highly porous and be great candidate materials for gas adsorption, molecular separation, catalysis, chemical sensing and drug delivery. Currently, there are still some limiting factors that impede the COP synthesis through DC_vC, and the most critical issue is that the dynamic covalent bonds formed are usually labile and cannot survive harsh conditions. Our research goals are to develop novel DC_vC methods utilizing more robust dynamic covalent bonds, and to construct shape-persistent molecular cages using such DC_vC methods. In Chapter 1, an overview is given of the current (state-of-art) development and applications of covalent organic cage molecules. The advantages of the DC_vC approach will be highlighted. In Chapter 2 the synthesis and aggregation study of shape-persistent phenylene vinylene macrocycles (PVMs) are described. With substitution groups varied, the PVMs exhibit very different aggregation behaviors, which help us to understand the structure-property relationship of this class of compounds. In Chapter 3, a porphyrin-based molecular prism is described, which is the first shapepersistent organic molecular cage prepared via alkyne metathesis.… Advisors/Committee Members: Wei Zhang, Douglas Gin, David Walba, Gordana Dukovic, Hai Long.

Subjects/Keywords: cage; dynamic covalent chemistry; fullerenes separation; macrocycle; porphyrin; Chemistry; Materials Science and Engineering

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APA (6^th Edition):

Zhang, C. (2014). Design, Synthesis, and Structure-Property Relationship Study of Shape-Persistent Phenylene Vinylene Macrocycles and Porphyrin-based Molecular Cages through Dynamic Covalent Chemistry. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/113

Chicago Manual of Style (16^th Edition):

Zhang, Chenxi. “Design, Synthesis, and Structure-Property Relationship Study of Shape-Persistent Phenylene Vinylene Macrocycles and Porphyrin-based Molecular Cages through Dynamic Covalent Chemistry.” 2014. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/113.

MLA Handbook (7^th Edition):

Zhang, Chenxi. “Design, Synthesis, and Structure-Property Relationship Study of Shape-Persistent Phenylene Vinylene Macrocycles and Porphyrin-based Molecular Cages through Dynamic Covalent Chemistry.” 2014. Web. 17 Apr 2021.

Vancouver:

Zhang C. Design, Synthesis, and Structure-Property Relationship Study of Shape-Persistent Phenylene Vinylene Macrocycles and Porphyrin-based Molecular Cages through Dynamic Covalent Chemistry. [Internet] [Doctoral dissertation]. University of Colorado; 2014. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/113.

Council of Science Editors:

Zhang C. Design, Synthesis, and Structure-Property Relationship Study of Shape-Persistent Phenylene Vinylene Macrocycles and Porphyrin-based Molecular Cages through Dynamic Covalent Chemistry. [Doctoral Dissertation]. University of Colorado; 2014. Available from: https://scholar.colorado.edu/chem_gradetds/113

University of Colorado

9. Ryerson, Joseph L. Structural and Photophysical Considerations of Singlet Fission Organic Thin Films for Solar Photochemsitry.

Degree: PhD, Chemistry & Biochemistry, 2016, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/194

► Singlet fission (SF) is a multichromophore charge multiplication process in organic systems in which a singlet exciton shares its energy with a neighboring chromophore,… (more)

▼ Singlet fission (SF) is a multichromophore charge multiplication process in organic systems in which a singlet exciton shares its energy with a neighboring chromophore, thus generating two triplet excitons from one photon. SF chromophores can boost photocurrent in solar cells, raising the maximum theoretical power conversion efficiency of a single-junction solar cell from ~33% to ~45. Thin film (TF) preparation techniques, steady-state and time-resolved spectroscopic methods, and numerous advanced calculations were used to study the three systems presented here, all of which exhibit polymorphism. TFs of 1,3-diphenylisobenzofuran (1), were prepared and two polymorphs, α-1 and β-1, were discovered and characterized. α-1films exhibit ΦT near 200% and low ΦF, whereas the dominant photophysical processes in the β-1 polymorph are prompt and excimer emissions, with ΦT around 10%. Absorption fitting revealed that the S1 state of β-1 is lower than α-1, and therefore SF and the correlated triplet 1(TT) is energetically inaccessible to β-1. The SF mechanism in TFs of each polymorph is outlined in great detail. Polymorphism in tetracene (Tc), a near 200% ΦT SF material, has been previously documented, although morphology considerations have been neglected. While crystallite size has been shown to affect dynamics, the two Tc polymorphs, I and II, have not been analyzed in a thorough comparison of dynamics and photophysics. Tc II films show SF rates that are independent of crystallite size and SF occurs more rapidly than in Tc I. The slower Tc I SF rates are highly dependent on grain size. Coupling calculations suggested that Tc I should be faster, but these calculations are limited,and more sophisticated, multimolecule calculations are needed to support experimental results. Two extremely stable indigo derivatives, Cibalackrot (2) and a tert-butylated derivative(3) were structurally and photophysically characterized in solution and in TFs. Two crystalline polymorphs (2α, 2β) and an amorphous phase (2a), as well as a crystalline (3α) and amorphous (3a) phase of 3 were deposited by thermal evaporation. ΦT values of less than 25% were observed for all morphologies, except in 2β(ΦT= 50%). Excimer formation dominates relaxation pathways in TFs of 2 and 3. Advisors/Committee Members: Arthur Nozik, Justin C. Johnson, Niels Damrauer, Gordana Dukovic, Sean Shaheen.

Subjects/Keywords: Singlet Fission; Solar; Spectroscopy; Thin Films; Triplet; Ultrafast; Chemistry; Materials Chemistry; Physical Chemistry

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APA (6^th Edition):

Ryerson, J. L. (2016). Structural and Photophysical Considerations of Singlet Fission Organic Thin Films for Solar Photochemsitry. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/194

Chicago Manual of Style (16^th Edition):

Ryerson, Joseph L. “Structural and Photophysical Considerations of Singlet Fission Organic Thin Films for Solar Photochemsitry.” 2016. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/194.

MLA Handbook (7^th Edition):

Ryerson, Joseph L. “Structural and Photophysical Considerations of Singlet Fission Organic Thin Films for Solar Photochemsitry.” 2016. Web. 17 Apr 2021.

Vancouver:

Ryerson JL. Structural and Photophysical Considerations of Singlet Fission Organic Thin Films for Solar Photochemsitry. [Internet] [Doctoral dissertation]. University of Colorado; 2016. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/194.

Council of Science Editors:

Ryerson JL. Structural and Photophysical Considerations of Singlet Fission Organic Thin Films for Solar Photochemsitry. [Doctoral Dissertation]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/chem_gradetds/194

University of Colorado

10. Ma, Ke. Photocatalytic Bionanomaterial for Renewable Energy.

Degree: PhD, Chemical & Biochemical Engineering, 2017, University of Colorado

URL: https://scholar.colorado.edu/chen_gradetds/14

► Photocatalytic materials and systems have been studied in recent years for generating fuels from renewable energy resources. My doctoral research has focused on studying the… (more)

Subjects/Keywords: photocatalytic bionanomaterial; renewable energy; Z-scheme; nanomaterial; alcohol dehydrogenase; Engineering

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APA (6^th Edition):

Ma, K. (2017). Photocatalytic Bionanomaterial for Renewable Energy. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chen_gradetds/14

Chicago Manual of Style (16^th Edition):

Ma, Ke. “Photocatalytic Bionanomaterial for Renewable Energy.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chen_gradetds/14.

MLA Handbook (7^th Edition):

Ma, Ke. “Photocatalytic Bionanomaterial for Renewable Energy.” 2017. Web. 17 Apr 2021.

Vancouver:

Ma K. Photocatalytic Bionanomaterial for Renewable Energy. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chen_gradetds/14.

Council of Science Editors:

Ma K. Photocatalytic Bionanomaterial for Renewable Energy. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/chen_gradetds/14

University of Colorado

11. Buckley, Danielle M. Carrier Dynamics of Colloidal Solutions and Arrays of Lead Chalcogenide Quantum Dots.

Degree: PhD, Chemistry & Biochemistry, 2014, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/121

► While quantum dots (QDs) potentially offer routes to increase the efficiency of solar energy harvesting, fundamental photophysical processes, such as carrier cooling, are still… (more)

Subjects/Keywords: degenerate pump probe; lead sulfide; quantum dots; ultrafast spectroscopy; Physical Chemistry

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APA (6^th Edition):

Buckley, D. M. (2014). Carrier Dynamics of Colloidal Solutions and Arrays of Lead Chalcogenide Quantum Dots. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/121

Chicago Manual of Style (16^th Edition):

Buckley, Danielle M. “Carrier Dynamics of Colloidal Solutions and Arrays of Lead Chalcogenide Quantum Dots.” 2014. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/121.

MLA Handbook (7^th Edition):

Buckley, Danielle M. “Carrier Dynamics of Colloidal Solutions and Arrays of Lead Chalcogenide Quantum Dots.” 2014. Web. 17 Apr 2021.

Vancouver:

Buckley DM. Carrier Dynamics of Colloidal Solutions and Arrays of Lead Chalcogenide Quantum Dots. [Internet] [Doctoral dissertation]. University of Colorado; 2014. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/121.

Council of Science Editors:

Buckley DM. Carrier Dynamics of Colloidal Solutions and Arrays of Lead Chalcogenide Quantum Dots. [Doctoral Dissertation]. University of Colorado; 2014. Available from: https://scholar.colorado.edu/chem_gradetds/121

University of Colorado

12. Macpherson, Hector Alexander. On the Chemical Synthesis and Physical Properties of Iron Pyrite, Especially the (100) Surface.

Degree: PhD, Mechanical Engineering, 2013, University of Colorado

URL: https://scholar.colorado.edu/mcen_gradetds/101

► Given that iron pyrite (cubic FeS₂, fool's gold) is a semiconductor with a ∼1 eV band gap, it has long been investigated for use… (more)

▼ Given that iron pyrite (cubic FeS₂, fool's gold) is a semiconductor with a ∼1 eV band gap, it has long been investigated for use in technological applications, especially photovoltaics. Unfortunately, numerous measurements indicate that it's properties, as currently synthesized at least, do not allow for effective devices. Photovoltages far below theoretical expectation are found as well as below band gap optical absorption. From a scientific standpoint, our understanding of the cause of these observations, the form of the density of states for instance, remains mired in uncertainty. In this work we have attempted to gain insight into this problem by creating ensembles of pyrite nanocrystals that can then be treated and measured with well-developed wet-chemical nanocrystal techniques. Specifically, we interpret the existing literature to advocate that the surface states of this material dominate its observed electrical properties. In an effort to better understand the most prevalent surface, the (100) face, we developed a synthesis that nucleates small (< 20 nm) pyrite nanoparticles and then changes chemical conditions to grow all other faces besides {100} to extinction, creating ∼37 nm nanocubes. The optical properties of these nanocubes are measured and the phenomenon of resonance light scattering (RLS) is observed. This phenomenon, along with the poor colloidal dispersibility of these nanocubes is then used to promote the idea that an unusual dynamic electronic phenomenon exists on these surfaces. This phenomenon is found to be passivated by introducing charged ligands to the surfaces of these particles. Additionally, after this surface treatment, two very sharp absorption features are observed at 0.73 and 0.88 eV. In connection with recent theoretical work, these transitions are taken as evidence that the (100) surface of pyrite is spin-polarized with each absorption peak being the signal of band edge absorption across a spin-selected direct band gap. A theoretical framework is proposed as a plausible explanation of the observed behavior. To wit, highly localized and energetically disordered Fe d-orbital states fill in the band gap of the (100) pyrite surface that is not perfectly terminated (or nearly so). Frustration between energetic disorder and Coulomb repulsion then results in the formation of metastable states that obscure the observation of these surface transitions and cause the dynamical behavior observed. It is further reasoned that one of these transitions, the one at 0.88 eV, has been observed before in cryogenic absorption and photoconductivity studies, and argued that a plausible reinterpretation of the data from these studies is possible. This reinterpretation can be rationalized within the context of the physical model posited here whereby cryogenic temperatures increase the importance of Coulombic interactions, which results in a decrease in the metastable DOS at the Fermi level and an electronic arrangement closer to that predicted theoretically, despite existing disorder.… Advisors/Committee Members: Conrad R. Stoldt, Gordana Dukovic, Yifu Ding, Todd Murray, Xiaobo Yin.

Subjects/Keywords: Materials Science and Engineering

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APA (6^th Edition):

Macpherson, H. A. (2013). On the Chemical Synthesis and Physical Properties of Iron Pyrite, Especially the (100) Surface. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/mcen_gradetds/101

Chicago Manual of Style (16^th Edition):

Macpherson, Hector Alexander. “On the Chemical Synthesis and Physical Properties of Iron Pyrite, Especially the (100) Surface.” 2013. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/mcen_gradetds/101.

MLA Handbook (7^th Edition):

Macpherson, Hector Alexander. “On the Chemical Synthesis and Physical Properties of Iron Pyrite, Especially the (100) Surface.” 2013. Web. 17 Apr 2021.

Vancouver:

Macpherson HA. On the Chemical Synthesis and Physical Properties of Iron Pyrite, Especially the (100) Surface. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/mcen_gradetds/101.

Council of Science Editors:

Macpherson HA. On the Chemical Synthesis and Physical Properties of Iron Pyrite, Especially the (100) Surface. [Doctoral Dissertation]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/mcen_gradetds/101

University of Colorado

13. Tienes, Bryan Matthew. Synthetic Methods for Nanomaterials of Controlled Composition and Morphology.

Degree: PhD, Chemistry & Biochemistry, 2013, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/144

► Novel heterogeneous catalysts are required to meet the energy needs of future generations and reduce emissions of carbon dioxide. Many of the recent advances… (more)

▼ Novel heterogeneous catalysts are required to meet the energy needs of future generations and reduce emissions of carbon dioxide. Many of the recent advances in catalysis have been in the study of nanoparticles. The catalytic activity of nanoparticles relies heavily on their composition, crystal morphology, and surface structure. The best approach for the discovery of new catalysts is to first identify the most catalytically active elemental compositions and then synthesize nanoparticles of those compositions in the most active morphology. This dissertation covers three projects, each with the goal of addressing deficiencies the methods currently available for that catalyst discovery approach. The work presented in Chapter 2 addressed deficiencies in the current synthetic methods used to discover materials with the most active composition. Presented is a method for synthesizing combinatorial catalysts arrays from precursor nanoparticles. Many researchers have turned to combinatorial methods to identify heterogeneous catalysts due to the difficultly in predicting active catalytic compositions a priori. First the synthetic method was demonstrated for generating arrays of gold and silver alloy nanoparticles, and then platinum and ruthenium nanoparticles were used to demonstrate the ability of the synthetic method to generate arrays for a combinatorial study. The final two chapters focused on understanding the role of capping ligands in nanoparticle synthesis and then utilizing their functionality to direct the synthesis of nanoparticles to produce a desired surface structure. Chapter 3 discusses the role of the popular capping ligands, alkyl phosphonic acids, in the synthesis of anisotropic zinc oxide nanoparticles. Chapter 4 describes work with the goal of using in vitro selection procedures to select RNA capable of directing the growth of platinum nanoparticles so that the desired surface structure is exposed on the surface of the nanoparticle product. Advisors/Committee Members: Daniel L. Feldheim, Gordana Dukovic, Cortlandt Peirpont, David Walba, Prashant Nagpal.

Subjects/Keywords: Chemistry; Nanotechnology

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APA (6^th Edition):

Tienes, B. M. (2013). Synthetic Methods for Nanomaterials of Controlled Composition and Morphology. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/144

Chicago Manual of Style (16^th Edition):

Tienes, Bryan Matthew. “Synthetic Methods for Nanomaterials of Controlled Composition and Morphology.” 2013. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/144.

MLA Handbook (7^th Edition):

Tienes, Bryan Matthew. “Synthetic Methods for Nanomaterials of Controlled Composition and Morphology.” 2013. Web. 17 Apr 2021.

Vancouver:

Tienes BM. Synthetic Methods for Nanomaterials of Controlled Composition and Morphology. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/144.

Council of Science Editors:

Tienes BM. Synthetic Methods for Nanomaterials of Controlled Composition and Morphology. [Doctoral Dissertation]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/chem_gradetds/144

University of Colorado

14. Wilker, Molly Bea. Charge Transfer Dynamics in Complexes of Light-Absorbing CdS Nanorods and Redox Catalysts.

Degree: PhD, Chemistry & Biochemistry, 2015, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/154

► The use of photoexcited electrons and holes in semiconductor nanocrystals as reduction and oxidation reagents is an intriguing way of harvesting photon energy to… (more)

▼ The use of photoexcited electrons and holes in semiconductor nanocrystals as reduction and oxidation reagents is an intriguing way of harvesting photon energy to drive chemical reactions. This dissertation describes research efforts to understand the photoexcited charge transfer kinetics in complexes of colloidal CdS nanorods coupled with either a water oxidation or reduction catalyst. The first project focuses on the charge transfer interactions between photoexcited CdS nanorods and a mononuclear water oxidation catalyst derived from the [Ru(bpy)(tpy)Cl]⁺ parent structure. Upon excitation, hole transfer from CdS oxidizes the catalyst (Ru²⁺→Ru³⁺) on a 100 ps – 1 ns timescale. This is followed by a 10 – 100 ns electron transfer that reduces the Ru³⁺ center. The relatively slow electron transfer dynamics may provide opportunities for accumulation of the multiple holes at the catalyst, which is necessary for water oxidation. The second project details the electron transfer kinetics in complexes of CdS nanorods coupled with [FeFe]-hydrogenase, which catalyzes H⁺ reduction. These complexes photochemically produce H₂ with quantum yields of up to 20%. The kinetics of electron transfer from CdS nanorods to hydrogenase play a critical role in the overall photochemical reactivity, as the quantum efficiency of electron transfer defines the upper limit on the quantum yield of H₂ generation. For optimized complexes, the electron transfer rate constant and the electron relaxation rate constant in CdS nanorods are comparable, with values of ≈107 s⁻¹, resulting in a quantum efficiency of electron transfer of 42%. Insights from these time-resolved spectroscopic studies are used to discuss the intricate kinetic pathways involved in photochemical H₂ generation in photocatalytic complexes. Finally, experimental results from photodriven H₂ generation and measurements of nanocrystal excited state lifetimes when the length of the nanocrystal-surface ligand was varied provide a deeper understanding into the mechanism for electron transfer from photoexcited nanorods to hydrogenase. Advisors/Committee Members: Gordana Dukovic, Niels Damrauer, David Jonas, Joel Eaves, Paul King.

Subjects/Keywords: Biomimetic; Photoluminescence; Transient Absorption; Chemistry; Nanoscience and Nanotechnology; Physical Chemistry

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APA (6^th Edition):

Wilker, M. B. (2015). Charge Transfer Dynamics in Complexes of Light-Absorbing CdS Nanorods and Redox Catalysts. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/154

Chicago Manual of Style (16^th Edition):

Wilker, Molly Bea. “Charge Transfer Dynamics in Complexes of Light-Absorbing CdS Nanorods and Redox Catalysts.” 2015. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/154.

MLA Handbook (7^th Edition):

Wilker, Molly Bea. “Charge Transfer Dynamics in Complexes of Light-Absorbing CdS Nanorods and Redox Catalysts.” 2015. Web. 17 Apr 2021.

Vancouver:

Wilker MB. Charge Transfer Dynamics in Complexes of Light-Absorbing CdS Nanorods and Redox Catalysts. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/154.

Council of Science Editors:

Wilker MB. Charge Transfer Dynamics in Complexes of Light-Absorbing CdS Nanorods and Redox Catalysts. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/chem_gradetds/154

University of Colorado

15. Schnitzenbaumer, Kyle J. The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots.

Degree: PhD, Chemistry & Biochemistry, 2015, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/159

► Quantum dots (QDs) are the foundation of many optoelectronic devices because their optical and electronic properties are synthetically tunable. The inherent connection between synthetically… (more)

Subjects/Keywords: Chalcogenide Ligands; Photophysics; Quantum Dots; Transient Absorption Spectroscopy; Physical Chemistry

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APA (6^th Edition):

Schnitzenbaumer, K. J. (2015). The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/159

Chicago Manual of Style (16^th Edition):

Schnitzenbaumer, Kyle J. “The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots.” 2015. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/159.

MLA Handbook (7^th Edition):

Schnitzenbaumer, Kyle J. “The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots.” 2015. Web. 17 Apr 2021.

Vancouver:

Schnitzenbaumer KJ. The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/159.

Council of Science Editors:

Schnitzenbaumer KJ. The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/chem_gradetds/159

University of Colorado

16. Smith, Candice Ashley. Nanoscale Reagents for the Detection and Treatment of Tuberculosis in Resource Limited Regions.

Degree: PhD, Chemistry & Biochemistry, 2015, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/173

► Tuberculosis (TB) remains the second deadliest infectious disease after HIV/AIDS. TB most stubbornly has been spreading in resource limited regions. People in these regions… (more)

Subjects/Keywords: SELEX; Sub-Saharan Africa; Middle East; developing countries; emerging infectious disease; Animal Sciences; Biochemistry; Chemistry

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APA (6^th Edition):

Smith, C. A. (2015). Nanoscale Reagents for the Detection and Treatment of Tuberculosis in Resource Limited Regions. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/173

Chicago Manual of Style (16^th Edition):

Smith, Candice Ashley. “Nanoscale Reagents for the Detection and Treatment of Tuberculosis in Resource Limited Regions.” 2015. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/173.

MLA Handbook (7^th Edition):

Smith, Candice Ashley. “Nanoscale Reagents for the Detection and Treatment of Tuberculosis in Resource Limited Regions.” 2015. Web. 17 Apr 2021.

Vancouver:

Smith CA. Nanoscale Reagents for the Detection and Treatment of Tuberculosis in Resource Limited Regions. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/173.

Council of Science Editors:

Smith CA. Nanoscale Reagents for the Detection and Treatment of Tuberculosis in Resource Limited Regions. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/chem_gradetds/173

University of Colorado

17. Utterback, James Keller. Excited-State Dynamics of Semiconductor Nanocrystals: Trapped-Hole Diffusion and Electron-Transfer Kinetics in CdS and CdSe Nanorods.

Degree: PhD, 2018, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/249

► Colloidal semiconductor nanocrystals have many remarkable properties—such as exceptionally tunable excited states and surface chemistry—that have led to an enthusiastic interest in using them for… (more)

▼ Colloidal semiconductor nanocrystals have many remarkable properties—such as exceptionally tunable excited states and surface chemistry—that have led to an enthusiastic interest in using them for optoelectronic applications such as solar-energy conversion. Such technologies require control over the generation, separation, and extraction of photoexcited electrons and holes. However, the interpretation of experimentally measured excited-state decay curves is challenging because they typically exhibit complicated shapes that are elusive to simple kinetic models. To understand the principles that govern electron and hole relaxation dynamics in these complex systems, models rooted in fundamental physical phenomena are needed. This dissertation describes efforts to understand the dynamics of recombination, charge carrier trapping, trapped holes, and charge transfer in photoexcited Cd-chalcogenide nanocrystals using a combination of ultrafast spectroscopy and kinetic modeling. The first part of this dissertation focuses on studying the spatial dynamics of trapped holes. In CdS and CdSe nanocrystals, photoexcited holes rapidly and efficiently trap to localized states on the surface. We demonstrate evidence that trapped holes are mobile in CdS nanorods, CdSe nanorods, and CdSe/CdS and ZnSe/CdS dot-in-rod heterostructures, and that they likely undergo a diffusive random walk between trap sites on the nanocrystal surface. The second part of the dissertation focuses on modeling charge-transfer kinetics in heterogeneous ensembles of donor–acceptor complexes. In complexes of CdS nanorods and [FeFe] hydrogenase, electron transfer is the key step for photochemical H₂ production. By accounting for the distributions in the numbers of electron traps and enzymes adsorbed, we determine the rate constants and quantum efficiencies for electron transfer. The relatively simple analytical models developed here establish a detailed conceptual and quantitative picture of the rich carrier dynamics in these systems, providing important insights for the design of semiconductor nanocrystals for light-driven applications. Advisors/Committee Members: Gordana Dukovic, Joel D. Eaves, Niels H. Damrauer, David M. Jonas, Garry Rumbles.

Subjects/Keywords: nanocrystals; photochemistry; photophysics; solar energy; ultrafast spectroscopy; Chemistry; Nanoscience and Nanotechnology; Physical Chemistry

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APA (6^th Edition):

Utterback, J. K. (2018). Excited-State Dynamics of Semiconductor Nanocrystals: Trapped-Hole Diffusion and Electron-Transfer Kinetics in CdS and CdSe Nanorods. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/249

Chicago Manual of Style (16^th Edition):

Utterback, James Keller. “Excited-State Dynamics of Semiconductor Nanocrystals: Trapped-Hole Diffusion and Electron-Transfer Kinetics in CdS and CdSe Nanorods.” 2018. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/249.

MLA Handbook (7^th Edition):

Utterback, James Keller. “Excited-State Dynamics of Semiconductor Nanocrystals: Trapped-Hole Diffusion and Electron-Transfer Kinetics in CdS and CdSe Nanorods.” 2018. Web. 17 Apr 2021.

Vancouver:

Utterback JK. Excited-State Dynamics of Semiconductor Nanocrystals: Trapped-Hole Diffusion and Electron-Transfer Kinetics in CdS and CdSe Nanorods. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/249.

Council of Science Editors:

Utterback JK. Excited-State Dynamics of Semiconductor Nanocrystals: Trapped-Hole Diffusion and Electron-Transfer Kinetics in CdS and CdSe Nanorods. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/chem_gradetds/249

University of Colorado

18. Fatur, Steven M. Tuning Iron(II) Excited States with Bulky Ligands and Investigating Chromium(III) Photocatalytic Mechanisms for Earth-Abundant Photocatalysis.

Degree: PhD, 2018, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/266

► Photocatalysis opens up new synthetic pathways and is a potential method for storing solar energy in chemical bonds. Many transition metal photocatalysts utilize long-lived… (more)

▼ Photocatalysis opens up new synthetic pathways and is a potential method for storing solar energy in chemical bonds. Many transition metal photocatalysts utilize long-lived metal-to-ligand charge transfer (MLCT) states as the catalytically active state. However, earth-abundant Fe(II) analogues of successful Ru(II) photocatalysts are plagued by ultrafast relaxation. Decreased ligand-field splitting in these first-row metal complexes opens new relaxation pathways via low-lying metal-centered states. To design potential photocatalysts with Fe(II) centers we chose to exploit the decreased ligand-field splitting by destabilizing the singlet state until the lowest energy quintet state became the ground state, opening up a distinct dynamical picture and lengthening the MLCT excited-state lifetime. In general, this class of complexes displays a > 100-fold improvement relative to the ~100 fs MLCT lifetime of the low-spin parent, Fe(II) bis-terpyridine. This is accomplished using a sterically demanding bis-terpyridyl ligand framework in which interligand repulsion destabilizes lower spin states to force the quintet ground state. Furthermore, this framework is easily altered synthetically by employing substituents with either steric or electronic effects, allowing for substantial tunability. We have systematically synthesized a range of these compounds and investigated them using x-ray crystallography, electrochemistry, magnetic measurements, and transient absorption spectroscopy. Through this effort, we highlight a novel approach to controlling excited-state dynamics and ground-state absorption in Fe(II) polypyridines with potential photocatalysis applications. A secondary project explores the mechanisms of Cr(III) photocatalyzed [4+2] cycloadditions. Cr(III) polypyridyl complexes have been found to serve as replacements for more expensive Ru(II) photocatalysts in these reactions. However, their application to a wider scope of reactions is limited by a lack of mechanistic understanding. With static and time-resolved photoluminescence spectroscopy and Stern-Volmer quenching studies, we show that [Cr(Ph₂phen)₃]³+ (Ph₂phen = 4,7-diphenyl-phenanthroline) is a potent photooxidant for promoting radical cation Diels-Alder reactions. Further experiments show that atmospheric oxygen is critical for turning over the catalyst. Finally, the mechanistic study of a related reaction with the same catalyst suggests that an energy transfer mechanism is also feasible in certain cases. This broader understanding of mechanistic pathways uncovers a rich vein for further mechanistic studies and Cr(III) catalyst development. Advisors/Committee Members: Niels H. Damrauer, Oana R. Luca, Michael P. Marshak, Gordana Dukovic, Matthew P. Shores.

Subjects/Keywords: chromium(iii); excited-state lifetimes; high-spin iron(ii); iron(ii) terpyridyl; photocatalyst; quintet mlct; Chemistry; Inorganic Chemistry

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APA (6^th Edition):

Fatur, S. M. (2018). Tuning Iron(II) Excited States with Bulky Ligands and Investigating Chromium(III) Photocatalytic Mechanisms for Earth-Abundant Photocatalysis. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/266

Chicago Manual of Style (16^th Edition):

Fatur, Steven M. “Tuning Iron(II) Excited States with Bulky Ligands and Investigating Chromium(III) Photocatalytic Mechanisms for Earth-Abundant Photocatalysis.” 2018. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/266.

MLA Handbook (7^th Edition):

Fatur, Steven M. “Tuning Iron(II) Excited States with Bulky Ligands and Investigating Chromium(III) Photocatalytic Mechanisms for Earth-Abundant Photocatalysis.” 2018. Web. 17 Apr 2021.

Vancouver:

Fatur SM. Tuning Iron(II) Excited States with Bulky Ligands and Investigating Chromium(III) Photocatalytic Mechanisms for Earth-Abundant Photocatalysis. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/266.

Council of Science Editors:

Fatur SM. Tuning Iron(II) Excited States with Bulky Ligands and Investigating Chromium(III) Photocatalytic Mechanisms for Earth-Abundant Photocatalysis. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/chem_gradetds/266

University of Colorado

19. Grennell, Amanda N. Photophysics and Electron Transfer Dynamics of Type-II and Quasi Type-II Heterostructure Nanocrystals.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/269

► Type-II and quasi type-II heterostructure nanocrystals are known to exhibit extended excited-state lifetimes compared to their single material counterparts because of reduced wavefunction overlap between… (more)

▼ Type-II and quasi type-II heterostructure nanocrystals are known to exhibit extended excited-state lifetimes compared to their single material counterparts because of reduced wavefunction overlap between the electron and hole. Thus, type-II heterostructures are promising materials for solar-to-fuel conversion, as extended excited-state lifetimes make transfer of charges to a catalyst more competitive with intrinsic nanocrystal decay processes. However, due to fast and efficient hole trapping and non-uniform morphologies, the photophysics of dot-in-rod heterostructures are more rich and complex than this simple picture. Using transient absorption spectroscopy, we observe that the behavior of electrons in the CdS “rod” or “bulb” regions of non-uniform ZnSe/CdS and CdSe/CdS dot-in-rods is similar regardless of the “dot” material, which supports previous work demonstrating that hole trapping and particle morphology drive electron dynamics. Furthermore, we show that the longest lived state in these dot-in-rods is not generated by the type-II or quasi type-II band alignment between the dot and the rod, but rather by electron-hole dissociation that occurs due to fast hole trapping in the CdS rod and electron localization to the bulb. We propose that specific variations in particle morphology and surface chemistry determine the mechanism and efficiency of charge separation and recombination in these nanostructures, and therefore impact their excited-state dynamics to a greater extent than the heterostructure energy level alignment alone. When coupled to a [Fe-Fe] hydrogenase, which catalyzes reduction of protons to H₂, we observe faster rates of electron transfer and higher quantum efficiency of electron transfer with CdSe/CdS and ZnSe/CdS dot-in-rods, but only from the bulb and interface states. Furthermore, the total efficiency of electron transfer of the ensemble is highest when the bulb/interface state is directly populated. This indicates that the bulb morphology is essential to efficient electron transfer in a dot-in-rod hydrogenase system. Advisors/Committee Members: Gordana Dukovic, Joel D. Eaves, Mathias M. Weber, Niels H. Damrauer, Margaret M. Murnane.

Subjects/Keywords: electron transfer; heterostructures; nanocrystals; nanorods; photophysics; ultrafast spectroscopy; Nanoscience and Nanotechnology; Physical Chemistry

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APA (6^th Edition):

Grennell, A. N. (2017). Photophysics and Electron Transfer Dynamics of Type-II and Quasi Type-II Heterostructure Nanocrystals. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/269

Chicago Manual of Style (16^th Edition):

Grennell, Amanda N. “Photophysics and Electron Transfer Dynamics of Type-II and Quasi Type-II Heterostructure Nanocrystals.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/269.

MLA Handbook (7^th Edition):

Grennell, Amanda N. “Photophysics and Electron Transfer Dynamics of Type-II and Quasi Type-II Heterostructure Nanocrystals.” 2017. Web. 17 Apr 2021.

Vancouver:

Grennell AN. Photophysics and Electron Transfer Dynamics of Type-II and Quasi Type-II Heterostructure Nanocrystals. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/269.

Council of Science Editors:

Grennell AN. Photophysics and Electron Transfer Dynamics of Type-II and Quasi Type-II Heterostructure Nanocrystals. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/chem_gradetds/269

University of Colorado

20. Pearce, Orion Magruder. Photoinduced Hole Transfer and Recombination Dynamics of a Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst.

Degree: PhD, 2019, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/297

► Artificial photosynthesis represents a promising strategy to capture and store solar energy through the production of carbon neutral fuels. This process begins with absorption of… (more)

▼ Artificial photosynthesis represents a promising strategy to capture and store solar energy through the production of carbon neutral fuels. This process begins with absorption of a photon by a semiconductor creating an electron-hole pair which are then separated and used to drive reduction and oxidation reactions. CdS nanostructures are model light absorbers for studying these charge transfer reactions and have already demonstrated photoinduced electron transfer to drive a variety of reactions. However, there has been comparatively little progress in understanding how CdS nanostructures may be used to sensitize oxidation reactions such as water oxidation. To this end, we undertook a thorough study of the excited state charge transfer behavior of a model system consisting of a mononuclear Ru water oxidation catalyst attached to the surface of a CdS quantum dot. Through careful analysis of the electron and hole sensitive measurements, we were able to determine parameters relevant for successful water oxidation. The first part of this dissertation consists of a study on the rate and efficiency of hole transfer to the catalyst. By modelling time resolved and steady state emission data it was discovered that the catalyst strongly binds to the quantum dot and engages in rapid photoinduced-hole transfer. The efficiency of hole transfer is limited only by competition with the tendency of holes to localize to quantum dot surface trap states. The second part of this dissertation determines the fate of the electron and hole following hole trapping or transfer. The population of quantum dots that transferred holes was found to decay to the ground state over the course of nanoseconds, while hole trapping appears to facilitate electron transfer to the catalyst. The final part of this dissertation explores the binding between quantum dot and catalyst using NMR spectroscopy. The two bind in a specific orientation which appears to facilitate hole transfer by provide a charge transfer pathway between the electronic states of the catalyst and quantum dot. This work establishes data analysis methods and design principles which may be leveraged in the development of future catalyst/quantum dot systems. Advisors/Committee Members: Gordana Dukovic, Niels H. Damrauer, Jennifer N. Cha, Michael P. Marshak, Garry Rumbles.

Subjects/Keywords: artificial photosynthesis; cadmium sulfide; hole transfer; quantum dot; ruthenium complex; water oxidation; Chemistry; Nanoscience and Nanotechnology; Physical Chemistry

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APA (6^th Edition):

Pearce, O. M. (2019). Photoinduced Hole Transfer and Recombination Dynamics of a Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/297

Chicago Manual of Style (16^th Edition):

Pearce, Orion Magruder. “Photoinduced Hole Transfer and Recombination Dynamics of a Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst.” 2019. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/297.

MLA Handbook (7^th Edition):

Pearce, Orion Magruder. “Photoinduced Hole Transfer and Recombination Dynamics of a Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst.” 2019. Web. 17 Apr 2021.

Vancouver:

Pearce OM. Photoinduced Hole Transfer and Recombination Dynamics of a Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst. [Internet] [Doctoral dissertation]. University of Colorado; 2019. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/297.

Council of Science Editors:

Pearce OM. Photoinduced Hole Transfer and Recombination Dynamics of a Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst. [Doctoral Dissertation]. University of Colorado; 2019. Available from: https://scholar.colorado.edu/chem_gradetds/297

University of Colorado

21. Courtney, Trevor Laurence. Bringing Two-Dimensional Fourier Transform Electronic Spectroscopy into the Short-Wave Infrared.

Degree: PhD, Chemistry & Biochemistry, 2012, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/69

► Two-dimensional Fourier Transform (2D FT) spectroscopy in the short-wave infrared (1-2 &mu) enables high frequency and time resolution experiments of molecular dyes, third-generation photovoltaic… (more)

▼ Two-dimensional Fourier Transform (2D FT) spectroscopy in the short-wave infrared (1-2 &mu) enables high frequency and time resolution experiments of molecular dyes, third-generation photovoltaic systems, and carotenoids - all rich in electronic transitions in this spectral region. Such experiments require short pulses with broad spectra to probe fast dephasing or solvation dynamics as well as couplings between widely spaced electronic transitions. Stable, low-dispersion interferometers at Brewster's angle are introduced for multioctave-spanning nonlinear spectroscopies. We adapt a compact, phase-characterized Mach-Zehnder interferometer to the short-wave infrared; active stabilization produces accurate and evenly spaced time delays between the two excitation pulses in 2D FT spectroscopy. An intrinsically phase-stable Sagnac interferometer is introduced to enhance the interferometric signal detection with respect to the copropagating local oscillator in partially collinear 2D FT spectroscopy. These interferometers exploit the air-glass interface Brewster's angle of thin-film metallic beam splitters to preserve expected output phase shifts and to minimize secondary reflections over multiple octaves. A homebuilt short-wave IR noncollinear optical parametric amplifier with a periodically poled crystal provides broadband excitation and detection. The output pulses are compressed with a deformable mirror using second-harmonic generation feedback in a genetic algorithm to pulse durations as low as 10 fs. Together this light source and the interferometric 2D spectrometer have enabled the first 2D FT electronic spectroscopy in this wavelength range; we analyze the early time solvation dynamics of IR-26 dye. Agreement between experimental and simulated purely absorptive 2D spectra of this dye proves the feasibility of the spectrometer design. Accurate evolution time delays in the partially collinear geometry reduce ambiguities in the phasing of these 2D spectra. Finally, initial 2D spectra of lead chalcogenide quantum dots exhibit first exciton transition (bleach) peaks; weak negative peaks potentially reflect biexciton shifts. These spectra lay the groundwork for broadband 2D FT spectroscopy to find exciton couplings and dephasing rates to help establish the mechanism of carrier multiplication for high-efficiency photovoltaics. Advisors/Committee Members: David M. Jonas, Steven T. Cundiff, Niels H. Damrauer, Gordana Dukovic, Robert P. Parson.

Subjects/Keywords: Interferometry; Short-Wave Infrared; Two-Dimensional Spectroscopy; Optics; Physical Chemistry

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APA (6^th Edition):

Courtney, T. L. (2012). Bringing Two-Dimensional Fourier Transform Electronic Spectroscopy into the Short-Wave Infrared. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/69

Chicago Manual of Style (16^th Edition):

Courtney, Trevor Laurence. “Bringing Two-Dimensional Fourier Transform Electronic Spectroscopy into the Short-Wave Infrared.” 2012. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/69.

MLA Handbook (7^th Edition):

Courtney, Trevor Laurence. “Bringing Two-Dimensional Fourier Transform Electronic Spectroscopy into the Short-Wave Infrared.” 2012. Web. 17 Apr 2021.

Vancouver:

Courtney TL. Bringing Two-Dimensional Fourier Transform Electronic Spectroscopy into the Short-Wave Infrared. [Internet] [Doctoral dissertation]. University of Colorado; 2012. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/69.

Council of Science Editors:

Courtney TL. Bringing Two-Dimensional Fourier Transform Electronic Spectroscopy into the Short-Wave Infrared. [Doctoral Dissertation]. University of Colorado; 2012. Available from: https://scholar.colorado.edu/chem_gradetds/69

University of Colorado

22. Tseng, Huan-Wei. Photophysical Studies of Chromium Sensitizers Designed for Excited State Hole Transfer to Semiconductors and Sequential Hole/Electron Transfers from Photoexcited Cadmium Sulfide Nanorods to Mononuclear Ruthenium Water-Oxidation Catalysts.

Degree: PhD, Chemical & Biochemical Engineering, 2013, University of Colorado

URL: https://scholar.colorado.edu/chbe_gradetds/38

► This dissertation describes three research projects related to solar cells and solar water splitting with a goal of utilizing solar energy, a renewable energy… (more)

▼ This dissertation describes three research projects related to solar cells and solar water splitting with a goal of utilizing solar energy, a renewable energy source. The first project is focused on photophysical studies of four newly-synthesized Cr(III) tris-bipyridyl complexes featuring the 4-dmcbpy (dimethyl 2,2'-bipyridine-4,4'-dicarboxylate) ligand. Static and time-resolved emission results suggest that the complexes store ~1.7 eV of energy for multiple microseconds. Using cyclic voltammetry, it is found that the inclusion of 4-dmcbpy shifts the E_1/2 of CrIII/II by +0.2 V from the homoleptic parent complexes without 4-dmcbpy. All four complexes have excited state potentials of CrIII*/II between +1.8 and +2.0 V vs. NHE, placing them among the most powerful photooxidants reported and making them candidates for hole-injection sensitizers. The second project continues with Cr(III) complexes, but using iminopyridine Schiff base ligands. Two complexes feature hexadentate ligands and the other two are their tris-bidentate analogues. One of each pair contains methyl ester groups for attachment to semiconductors. Cyclic voltammograms show that the hexadentate and tris-bidentate analogues have almost identical reduction potentials, but the addition of ester substituents shifts the reduction potentials by +0.2 V. The absorption spectra of the hexadentate complexes show improved absorption of visible light compared to the tris-bidentate analogues. For freshly prepared sample solutions in CH₃CN, time-resolved emission and transient absorption measurements for the Cr(III) tris-bidentate ester complex show a doublet excited state with a 17-19 microsecond lifetime at room temperature, while no emission or transient absorption signals from the doublet states are observed for the hexadentate analogue under the same conditions. The dramatic difference is due to the presence of a nonligated bridgehead nitrogen atom. The third project features charge transfer interactions between a photoexcited cadmium sulfide nanorod and [Ru(diethyl 2,2'-bipyridine-4,4'-dicarboxylate)(2,2':6',2"-terpyridine)Cl]+, a mononuclear water-oxidation catalyst. Upon photoexcitation, hole transfer from the cadmium sulfide nanorod oxidizes the catalyst (Ru2+ to Ru3+) on a 100 ps to 1 ns timescale. This is followed by electron transfer (10-100 ns) from the nanorod to reduce the Ru3+ center. The relatively slow electron transfer dynamics may provide opportunities for the accumulation of multiple holes at the catalyst, which is required for water oxidation. Advisors/Committee Members: Professor Niels H. Damrauer, Cortlandt G. Pierpont, Gordana Dukovic, Charles B. Musgrave, Wei Zhang.

Subjects/Keywords: Cadmium Sulfide; Chromium; Electron Transfer; Hole Transfer; Ruthenium

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

APA (6^th Edition):

Tseng, H. (2013). Photophysical Studies of Chromium Sensitizers Designed for Excited State Hole Transfer to Semiconductors and Sequential Hole/Electron Transfers from Photoexcited Cadmium Sulfide Nanorods to Mononuclear Ruthenium Water-Oxidation Catalysts. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chbe_gradetds/38

Chicago Manual of Style (16^th Edition):

Tseng, Huan-Wei. “Photophysical Studies of Chromium Sensitizers Designed for Excited State Hole Transfer to Semiconductors and Sequential Hole/Electron Transfers from Photoexcited Cadmium Sulfide Nanorods to Mononuclear Ruthenium Water-Oxidation Catalysts.” 2013. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chbe_gradetds/38.

MLA Handbook (7^th Edition):

Tseng, Huan-Wei. “Photophysical Studies of Chromium Sensitizers Designed for Excited State Hole Transfer to Semiconductors and Sequential Hole/Electron Transfers from Photoexcited Cadmium Sulfide Nanorods to Mononuclear Ruthenium Water-Oxidation Catalysts.” 2013. Web. 17 Apr 2021.

Vancouver:

Tseng H. Photophysical Studies of Chromium Sensitizers Designed for Excited State Hole Transfer to Semiconductors and Sequential Hole/Electron Transfers from Photoexcited Cadmium Sulfide Nanorods to Mononuclear Ruthenium Water-Oxidation Catalysts. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chbe_gradetds/38.

Council of Science Editors:

Tseng H. Photophysical Studies of Chromium Sensitizers Designed for Excited State Hole Transfer to Semiconductors and Sequential Hole/Electron Transfers from Photoexcited Cadmium Sulfide Nanorods to Mononuclear Ruthenium Water-Oxidation Catalysts. [Doctoral Dissertation]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/chbe_gradetds/38

University of Colorado

23. Abdulagatov, Aziz Ilmutdinovich. Growth, Characterization and Post-processing of Inorganic and Hybrid Organic-inorganic Thin Films Deposited using Atomic and Molecular Layer Deposition Techniques.

Degree: PhD, Chemistry & Biochemistry, 2012, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/83

► Atomic layer deposition (ALD) and molecular layer deposition (MLD) are advanced thin film coating techniques developed for deposition of inorganic and hybrid organic-inorganic films… (more)

▼ Atomic layer deposition (ALD) and molecular layer deposition (MLD) are advanced thin film coating techniques developed for deposition of inorganic and hybrid organic-inorganic films respectively. Decreasing device dimensions and increasing aspect ratios in semiconductor processing has motivated developments in ALD. The beginning of this thesis will cover study of new ALD chemistry for high dielectric constant Y₂O₃. In addition, the feasibility of conducting low temperature ALD of TiN and TiAlN is explored using highly reactive hydrazine as a new nitrogen source. Developments of these ALD processes are important for the electronics industry. As the search for new materials with more advanced properties continues, attention has shifted toward exploring the synthesis of hierarchically nanostructured thin films. Such complex architectures can provide novel functions important to the development of state of the art devices for the electronics industry, catalysis, energy conversion and memory storage as a few examples. Therefore, the main focus of this thesis is on the growth, characterization, and post-processing of ALD and MLD films for fabrication of novel composite (nanostructured) thin films. Novel composite materials are created by annealing amorphous ALD oxide alloys in air and by heat treatment of hybrid organic-inorganic MLD films in inert atmosphere (pyrolysis). The synthesis of porous TiO₂ or Al₂O₃ supported V₂O₅ for enhanced surface area catalysis was achieved by the annealing of inorganic TiV_xO_y and AlV_xO_y ALD films in air. The interplay between phase separation, surface energy difference, crystallization, and melting temperature of individual oxides were studied for their control of film morphology. In other work, a class of novel metal oxide-graphitic carbon composite thin films was produced by pyrolysis of MLD hybrid organic-inorganic films. For example, annealing in argon of titania based hybrid films enabled fabrication of thin films of intimately mixed TiO₂ and nanographitized carbon. The graphitized carbon in the film was formed as a result of the removal of hydrogen by pyrolysis of the organic constituency of the MLD film. The presence of graphitic carbon allowed a 14 orders of magnitude increase in the electrical conductivity of the composite material compared fully oxidized rutile TiO₂. Advisors/Committee Members: Steven M. George, Cortlandt G. Pierpont, Niels H. Damrauer, Gordana Dukovic, Rishi, Raj.

Subjects/Keywords: annealing; atomic layer deposition; hybrid organic-inorganic films; molecular layer deposition; post-processing; pyrolysis; Chemistry; Materials Chemistry; Physical Chemistry

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APA (6^th Edition):

Abdulagatov, A. I. (2012). Growth, Characterization and Post-processing of Inorganic and Hybrid Organic-inorganic Thin Films Deposited using Atomic and Molecular Layer Deposition Techniques. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/83

Chicago Manual of Style (16^th Edition):

Abdulagatov, Aziz Ilmutdinovich. “Growth, Characterization and Post-processing of Inorganic and Hybrid Organic-inorganic Thin Films Deposited using Atomic and Molecular Layer Deposition Techniques.” 2012. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/83.

MLA Handbook (7^th Edition):

Abdulagatov, Aziz Ilmutdinovich. “Growth, Characterization and Post-processing of Inorganic and Hybrid Organic-inorganic Thin Films Deposited using Atomic and Molecular Layer Deposition Techniques.” 2012. Web. 17 Apr 2021.

Vancouver:

Abdulagatov AI. Growth, Characterization and Post-processing of Inorganic and Hybrid Organic-inorganic Thin Films Deposited using Atomic and Molecular Layer Deposition Techniques. [Internet] [Doctoral dissertation]. University of Colorado; 2012. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/83.

Council of Science Editors:

Abdulagatov AI. Growth, Characterization and Post-processing of Inorganic and Hybrid Organic-inorganic Thin Films Deposited using Atomic and Molecular Layer Deposition Techniques. [Doctoral Dissertation]. University of Colorado; 2012. Available from: https://scholar.colorado.edu/chem_gradetds/83

University of Colorado

24. Hughes, Barbara Katherine. Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics.

Degree: PhD, Chemistry & Biochemistry, 2013, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/88

► Semiconductor quantum dots (QDs) are an interesting class of materials in that they exhibit unique physical properties when compared to their bulk counterparts. These… (more)

▼ Semiconductor quantum dots (QDs) are an interesting class of materials in that they exhibit unique physical properties when compared to their bulk counterparts. These unique properties and the breadth of tunability which they possess have made QD research a major field of study for more than 20 years for technologies such as catalysis, bio-imaging, solid-state lighting, and solar energy conversion. The primary concern for the application of semiconductor QDs in any field is not only to be able to precisely control physical properties (i.e., optical, electrical, magnetic) but also to understand how to achieve increased stability in these materials. A greater understanding of the chemistry of QD growth, surface construction, and composition are necessary to realize these goals. This thesis explores each of these areas of QD chemistry and the subsequent effects on their photophysical properties. Through manipulation of QD morphology, we have prepared PbSe QD dimers, which has allowed for a better understanding of electronic structure in quantum confined systems. Specifically we have observed a new absorption feature in the 1st exciton QD-dimer spectra, which we assign to a splitting of the 8-fold degenerate 1S level upon fusion of two monomer species. Surface treatment of PbSe QDs with a newly synthesized alkylselenide ligand has led to higher air stability, unique temperature dependent PL properties and the observation of a new surface-related trap level. Alongside producing more stable QDs, the nature of the strong Pb_surface to Se-R bond may also have implications for affecting kinetic processes like carrier relaxation, which could facilitate production of materials that show enhanced multiple exciton generation (MEG) yields. Finally, substitutional doping of PbSe QDs has allowed for modulation of QD compositions and in turn tuning of the dominant carrier type in both solution and in QD films. Although just a small contribution to the larger reservoir of work in this area, these results provide promise for improving stability and efficiency of QD devices for solar energy conversion. Advisors/Committee Members: Arthur J. Nozik, David M. Jonas, Garry Rumbles, Gordana Dukovic, Ivan Smalyukh.

Subjects/Keywords: morphology; photophysics; quantum dots; surface chemistry; Physical Chemistry

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APA (6^th Edition):

Hughes, B. K. (2013). Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/88

Chicago Manual of Style (16^th Edition):

Hughes, Barbara Katherine. “Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics.” 2013. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/88.

MLA Handbook (7^th Edition):

Hughes, Barbara Katherine. “Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics.” 2013. Web. 17 Apr 2021.

Vancouver:

Hughes BK. Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/88.

Council of Science Editors:

Hughes BK. Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics. [Doctoral Dissertation]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/chem_gradetds/88

University of Colorado

25. Gould, Troy Donald. Preparation of Supported Metal Catalysts by Atomic and Molecular Layer Deposition for Improved Catalytic Performance.

Degree: PhD, 2014, University of Colorado

URL: https://scholar.colorado.edu/chbe_gradetds/57

► Creating catalysts with enhanced selectivity and activity requires precise control over particle shape, composition, and size. Here we report the use of atomic layer… (more)

▼ Creating catalysts with enhanced selectivity and activity requires precise control over particle shape, composition, and size. Here we report the use of atomic layer deposition (ALD) to synthesize supported Ni, Pt, and Ni-Pt catalysts in the size regime (< 3 nm) where nanoscale properties can have a dramatic effect on reaction activity and selectivity. This thesis presents the first ALD synthesis of non-noble metal nanoparticles by depositing Ni on Al₂O₃ with two half-reactions of Ni(Cp)₂ and H₂. By changing the number of ALD cycles, Ni weight loadings were varied from 4.7 wt% to 16.7 wt% and the average particle sizes ranged from 2.5 to 3.3 nm, which increased the selectivity for C₃H₆ hydrogenolysis by an order of magnitude over a much larger Ni/Al₂O₃ catalyst. Pt particles were deposited by varying the number of ALD cycles and the reaction chemistry (H₂ or O₂) to control the particle size from approximately 1 to 2 nm, which allowed lower-coordinated surface atoms to populate the particle surface. These Pt ALD catalysts demonstrated some of the highest oxidative dehydrogenation of propane selectivities (37%) of a Pt catalyst synthesized by a scalable technique. Dry reforming of methane (DRM) is a reaction of interest due to the recent increased recovery of natural gas, but this reaction is hindered from industrial implementation because the Ni catalysts are plagued by deactivation from sintering and coking. This work utilized Ni ALD and NiPt ALD catalysts for the DRM reaction. These catalysts did not form destructive carbon whiskers and had enhanced reaction rates due to increased bimetallic interaction. To further limit sintering, the Ni and NiPt ALD catalysts were coated with a porous alumina matrix by molecular layer deposition (MLD). The catalysts were evaluated for DRM at 973 K, and the MLD-coated Ni catalysts outperformed the uncoated Ni catalysts in either activity (with 5 MLD cycles) or stability (with 10 MLD cycles). In summary, this thesis developed a new Ni nanoparticle ALD chemistry, explored possibilities for changing Pt ALD particle size, brought the two techniques together to create enhanced bimetallic catalysts, and stabilized the catalysts using MLD. Advisors/Committee Members: James W. Medlin, John L. Falconer, Alan W. Weimer, Charles B. Musgrave, Gordana Dukovic.

Subjects/Keywords: atomic layer deposition; dry reforming of methane; heterogeneous catalysis; molecular layer deposition; nanoparticles; oxidative dehydrogenation of propane; Chemical Engineering; Materials Science and Engineering; Nanoscience and Nanotechnology

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

APA (6^th Edition):

Gould, T. D. (2014). Preparation of Supported Metal Catalysts by Atomic and Molecular Layer Deposition for Improved Catalytic Performance. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chbe_gradetds/57

Chicago Manual of Style (16^th Edition):

Gould, Troy Donald. “Preparation of Supported Metal Catalysts by Atomic and Molecular Layer Deposition for Improved Catalytic Performance.” 2014. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chbe_gradetds/57.

MLA Handbook (7^th Edition):

Gould, Troy Donald. “Preparation of Supported Metal Catalysts by Atomic and Molecular Layer Deposition for Improved Catalytic Performance.” 2014. Web. 17 Apr 2021.

Vancouver:

Gould TD. Preparation of Supported Metal Catalysts by Atomic and Molecular Layer Deposition for Improved Catalytic Performance. [Internet] [Doctoral dissertation]. University of Colorado; 2014. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chbe_gradetds/57.

Council of Science Editors:

Gould TD. Preparation of Supported Metal Catalysts by Atomic and Molecular Layer Deposition for Improved Catalytic Performance. [Doctoral Dissertation]. University of Colorado; 2014. Available from: https://scholar.colorado.edu/chbe_gradetds/57

University of Colorado

26. Grumstrup, Erik Martin. Elucidation of Ultrafast Photophysics with Optical Pulse Shaping.

Degree: PhD, Physics, 2011, University of Colorado

URL: https://scholar.colorado.edu/phys_gradetds/182

► Optical pulse shaping is an incisive tool of laser spectroscopy that allows the experimentalist extensive flexibility to manipulate the electric field of an excitation… (more)

▼ Optical pulse shaping is an incisive tool of laser spectroscopy that allows the experimentalist extensive flexibility to manipulate the electric field of an excitation laser pulse. In this thesis, four applications of optical pulse shaping are examined. In Chapter 2, a partially non-collinear implementation of two-dimensional electronic spectroscopy is demonstrated for the first time on rubidium vapor. The use of a pulse shaper in this context is advantageous as it significantly reduces the complexity of the experimental apparatus. Unfortunately, non-ideal pulse shaping due to pixelation effects in some pulse-shaping devices leads to spurious pulse generation when the spatial masks become highly modulated. To model the effects on recovered 2D spectra, the optical Bloch model is numerically propagated with an explicit inclusion of the electric field modified by pixelation effects. Finally, steps necessary to minimize distortions are outlined. Chapter 3 describes a series of experiments designed to study the mechanism of multiple exciton generation in semiconductor quantum dots through open and closed loop coherent control schemes. The data collected with open loop control methods indicate that the initially formed exciton relaxes on an ultrafast time scale (<20 fs) revealing the reason for a lack of controllability in adaptive, closed-loop optimizations. Chapter 4 of this thesis examines the process of singlet fission in tetracene thin films employing coherent control and ultrafast pulse shaping. Singlet fission is a promising avenue to achieving highly efficient third generation photovoltaic devices, and in this work, closed-loop control suggests that low-frequency nuclear motions play a mechanistic role in tetracene singlet fission. Finally, Chapter 5 examines a specific class of pulse shaping, sinusoidal spectral phase modulation, which is widely employed in the coherent control community as a route toward an intuitive probe into molecular dynamics. This work seeks to build a bridge between the fields of nonlinear spectroscopy and coherent control by describing the light-matter interactions characteristic of this type of pulse shaping using the tools of time-dependent perturbation theory. This description allows experimentalists to predict and test theories of coherent control simply and with little ambiguity, furthering the usefulness of coherent control as a spectroscopic tool. Advisors/Committee Members: Niels H. Damrauer, David M. Jonas, Margaret Murnane, Gordana Dukovic, Joel Eaves.

Subjects/Keywords: 2DE spectroscopy; coherent control; pulse shaping; Optics; Physical Chemistry

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APA (6^th Edition):

Grumstrup, E. M. (2011). Elucidation of Ultrafast Photophysics with Optical Pulse Shaping. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/phys_gradetds/182

Chicago Manual of Style (16^th Edition):

Grumstrup, Erik Martin. “Elucidation of Ultrafast Photophysics with Optical Pulse Shaping.” 2011. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/phys_gradetds/182.

MLA Handbook (7^th Edition):

Grumstrup, Erik Martin. “Elucidation of Ultrafast Photophysics with Optical Pulse Shaping.” 2011. Web. 17 Apr 2021.

Vancouver:

Grumstrup EM. Elucidation of Ultrafast Photophysics with Optical Pulse Shaping. [Internet] [Doctoral dissertation]. University of Colorado; 2011. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/phys_gradetds/182.

Council of Science Editors:

Grumstrup EM. Elucidation of Ultrafast Photophysics with Optical Pulse Shaping. [Doctoral Dissertation]. University of Colorado; 2011. Available from: https://scholar.colorado.edu/phys_gradetds/182

University of Colorado

27. Marshall, Ashley R. Controlling the Photophysical Properties of Semiconductor Quantum Dot Arrays by Strategic Alteration of Their Surface Chemistry.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/205

► Semiconductor quantum dots (QDs) are interesting materials that, after less than 40 years of research, are used in commercial products. QDs are now found… (more)

▼ Semiconductor quantum dots (QDs) are interesting materials that, after less than 40 years of research, are used in commercial products. QDs are now found in displays, such as Samsung televisions and the Kindle Fire, and have applications in lighting, bio-imaging, quantum computing, and photovoltaics. They offer a large range of desirable properties: a controllable band gap, solution processability, controlled energy levels, and are currently the best materials for multiple exciton generation. The tunable optoelectronic properties of QDs can be controlled using size, shape, composition, and surface treatments—as shown here. Due to the quasi-spherical shape of QDs the surface to volume ratio is high, i.e. many of the constituent atoms are found on the QD surface. This makes QDs highly sensitive to surface chemistry modifications. This thesis encompasses the effects of surface treatments for QDs of two semiconducting materials: lead chalcogenides and CsPbI₃. Our group developed a new synthetic technique for lead chalcogenide QDs via the cation exchange of cadmium chalcogenides. An in-depth chemical analysis is paired with optical and electrical studies and we find that metal halide residue contributes to the oxidative stability and decreased trap state density in cation-exchanged PbS QDs. We exploit these properties to make air-stable QD photovoltaic devices from both PbS and PbSe QD materials. Beyond the effects of residual atoms left from the synthetic technique, I investigated how to controllably add atoms onto the surface of QDs. I found that by introducing metal halides as a post-treatment in an electronically coupled array I am able to control the performance parameters in QD photovoltaic devices. These treatments fully infiltrate the assembled film, even under short exposure times and allow me to add controlled quantities of surface atoms to study their effects on film properties and photovoltaic device performance. Finally, I sought to apply the knowledge of the lead chalcogenide QD surfaces to produce QD photovoltaics from a new material: CsPbI₃. I fabricated the first perovskite QD photovoltaic devices and using similar treatment methods as the lead chalcogenide QD arrays, I am able to influence the photophysical properties of CsPbI₃ QD arrays. Advisors/Committee Members: Arthur J. Nozik, Joseph M. Luther, Gordana Dukovic, Garry Rumbles, Michael Marshak.

Subjects/Keywords: lead selenide; lead sulfide; nanocrystal; perovskite; photovoltaic; quantum dot; Chemistry; Materials Science and Engineering; Nanoscience and Nanotechnology

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APA (6^th Edition):

Marshall, A. R. (2017). Controlling the Photophysical Properties of Semiconductor Quantum Dot Arrays by Strategic Alteration of Their Surface Chemistry. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/205

Chicago Manual of Style (16^th Edition):

Marshall, Ashley R. “Controlling the Photophysical Properties of Semiconductor Quantum Dot Arrays by Strategic Alteration of Their Surface Chemistry.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/205.

MLA Handbook (7^th Edition):

Marshall, Ashley R. “Controlling the Photophysical Properties of Semiconductor Quantum Dot Arrays by Strategic Alteration of Their Surface Chemistry.” 2017. Web. 17 Apr 2021.

Vancouver:

Marshall AR. Controlling the Photophysical Properties of Semiconductor Quantum Dot Arrays by Strategic Alteration of Their Surface Chemistry. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/205.

Council of Science Editors:

Marshall AR. Controlling the Photophysical Properties of Semiconductor Quantum Dot Arrays by Strategic Alteration of Their Surface Chemistry. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/chem_gradetds/205

University of Colorado

28. Cook, Jasper Donald. Informing Singlet Fission Chromophore Design via Photophysical Exploration of Tetracene and Tetracene-Inspired Covalent Dimers.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/206

► Singlet fission (SF) is a spin-allowed process wherein a singlet excited state on one molecule shares its energy with a neighbor to create a pair… (more)

Subjects/Keywords: covalent dimers; electronic coupling; photophysics; polyacenes; singlet fission; tetracene; Chemistry; Energy Systems; Physical Chemistry

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

APA (6^th Edition):

Cook, J. D. (2017). Informing Singlet Fission Chromophore Design via Photophysical Exploration of Tetracene and Tetracene-Inspired Covalent Dimers. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/206

Chicago Manual of Style (16^th Edition):

Cook, Jasper Donald. “Informing Singlet Fission Chromophore Design via Photophysical Exploration of Tetracene and Tetracene-Inspired Covalent Dimers.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/206.

MLA Handbook (7^th Edition):

Cook, Jasper Donald. “Informing Singlet Fission Chromophore Design via Photophysical Exploration of Tetracene and Tetracene-Inspired Covalent Dimers.” 2017. Web. 17 Apr 2021.

Vancouver:

Cook JD. Informing Singlet Fission Chromophore Design via Photophysical Exploration of Tetracene and Tetracene-Inspired Covalent Dimers. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/206.

Council of Science Editors:

Cook JD. Informing Singlet Fission Chromophore Design via Photophysical Exploration of Tetracene and Tetracene-Inspired Covalent Dimers. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/chem_gradetds/206

University of Colorado

29. Grennell, Amanda Norell. Photophysics and Electron Transfer Dynamics of Type-Ii and Quasi Type-Ii Heterostructure Nanocrystals.

Degree: PhD, Chemistry & Biochemistry, 2017, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/222

► Type-II and quasi type-II heterostructure nanocrystals are known to exhibit extended excited-state lifetimes compared to their single material counterparts because of reduced wavefunction overlap between… (more)

▼ Type-II and quasi type-II heterostructure nanocrystals are known to exhibit extended excited-state lifetimes compared to their single material counterparts because of reduced wavefunction overlap between the electron and hole. Thus, type-II heterostructures are promising materials for solar-to-fuel conversion, as extended excited-state lifetimes make transfer of charges to a catalyst more competitive with intrinsic nanocrystal decay processes. However, due to fast and efficient hole trapping and non-uniform morphologies, the photophysics of dot-in-rod heterostructures are more rich and complex than this simple picture. Using transient absorption spectroscopy, we observe that the behavior of electrons in the CdS “rod” or “bulb” regions of non-uniform ZnSe/CdS and CdSe/CdS dot-in-rods is similar regardless of the “dot” material, which supports previous work demonstrating that hole trapping and particle morphology drive electron dynamics. Furthermore, we show that the longest lived state in these dot-in-rods is not generated by the type-II or quasi type-II band alignment between the dot and the rod, but rather by electron-hole dissociation that occurs due to fast hole trapping in the CdS rod and electron localization to the bulb. We propose that specific variations in particle morphology and surface chemistry determine the mechanism and efficiency of charge separation and recombination in these nanostructures, and therefore impact their excited-state dynamics to a greater extent than the heterostructure energy level alignment alone. When coupled to a [Fe-Fe] hydrogenase, which catalyzes reduction of protons to H2, we observe faster rates of electron transfer and higher quantum efficiency of electron transfer with CdSe/CdS and ZnSe/CdS dot-in-rods, but only from the bulb and interface states. Furthermore, the total efficiency of electron transfer of the ensemble is highest when the bulb/interface state is directly populated. This indicates that the bulb morphology is essential to efficient electron transfer in a dot-in-rod hydrogenase system. Advisors/Committee Members: Gordana Dukovic, Joel D. Eaves, Mathias M. Weber, Niels H. Damrauer, Margaret M. Murnane.

Subjects/Keywords: Electron transfer; Heterostructures; Nanocrystals; Nanorods; Photophysics; Ultrafast spectroscopy; Nanoscience and Nanotechnology; Physical Chemistry

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

APA (6^th Edition):

Grennell, A. N. (2017). Photophysics and Electron Transfer Dynamics of Type-Ii and Quasi Type-Ii Heterostructure Nanocrystals. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/222

Chicago Manual of Style (16^th Edition):

Grennell, Amanda Norell. “Photophysics and Electron Transfer Dynamics of Type-Ii and Quasi Type-Ii Heterostructure Nanocrystals.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/222.

MLA Handbook (7^th Edition):

Grennell, Amanda Norell. “Photophysics and Electron Transfer Dynamics of Type-Ii and Quasi Type-Ii Heterostructure Nanocrystals.” 2017. Web. 17 Apr 2021.

Vancouver:

Grennell AN. Photophysics and Electron Transfer Dynamics of Type-Ii and Quasi Type-Ii Heterostructure Nanocrystals. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/222.

Council of Science Editors:

Grennell AN. Photophysics and Electron Transfer Dynamics of Type-Ii and Quasi Type-Ii Heterostructure Nanocrystals. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/chem_gradetds/222

University of Colorado

30. Kroupa, Daniel McCray. Manipulation of Colloidal Semiconductor Nanocrystal Optical and Electronic Properties Via Postynthetic Chemical Modification.

Degree: PhD, Chemistry & Biochemistry, 2017, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/225

► Colloidal semiconductor nanocrystals are a promising class of functional materials that have been the subject of intense research and development for over thirty years due… (more)

Subjects/Keywords: Physical Chemistry

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

APA (6^th Edition):

Kroupa, D. M. (2017). Manipulation of Colloidal Semiconductor Nanocrystal Optical and Electronic Properties Via Postynthetic Chemical Modification. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/225

Chicago Manual of Style (16^th Edition):

Kroupa, Daniel McCray. “Manipulation of Colloidal Semiconductor Nanocrystal Optical and Electronic Properties Via Postynthetic Chemical Modification.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 17, 2021. https://scholar.colorado.edu/chem_gradetds/225.

MLA Handbook (7^th Edition):

Kroupa, Daniel McCray. “Manipulation of Colloidal Semiconductor Nanocrystal Optical and Electronic Properties Via Postynthetic Chemical Modification.” 2017. Web. 17 Apr 2021.

Vancouver:

Kroupa DM. Manipulation of Colloidal Semiconductor Nanocrystal Optical and Electronic Properties Via Postynthetic Chemical Modification. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 17]. Available from: https://scholar.colorado.edu/chem_gradetds/225.

Council of Science Editors:

Kroupa DM. Manipulation of Colloidal Semiconductor Nanocrystal Optical and Electronic Properties Via Postynthetic Chemical Modification. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/chem_gradetds/225

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