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Dissertations / Theses on the topic 'Excited state chemistry'

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Published: 4 June 2021
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1

Potter, Charles Alan Stuart. "Excited state proton transfer in 2-substituted benzothiazoles." Thesis, University of Central Lancashire, 1993. http://clok.uclan.ac.uk/19742/.

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The photophysics of 2-(2'-hydroxyphenyl)benzothiazole (HBT) and related compounds has been studied as a function of solvent, pH or H 0 and temperature. Measurements of absorption and fluorescence spectra and fluorescence decay profiles under these various conditions have been combined with theoretical calculations to arrive at an understanding of the excited state behaviour of HBT and derivatives. An investigation has been made into the protonation and deprotonation of 2-phenylbenzothiazole, 2-(2'-methoxyphenyl)benzothiazole), HBT and derivatives of HBT with bromine, chlorine, hydroxy, methoxy, methyl and nitro substituents in the 2-phenyl ring. Absorption and fluorescence spectra have been combined with Forster cycle calculations to yield pKa, pKb, pKa* and pKb* values for the various compounds. The results have been compared with those for the corresponding phenols and many similarities noted. The overlap of the pK a* and pKb* values for HBT and derivatives has been noted. This has explained the occurrence of excited state intramolecular proton transfer (ESIPT) in these compounds. A study of the photophysics of HBT in non-polar and alcoholic mixtures for temperatures in the range 96-298K has been made using the Berlin synchrotron source, BESSY. In all solvents a rise in both fluorescence quantum yield and lifetime is observed as the temperature is decreased. It is proposed that a viscosity dependent non-radiative process leading to a nonemissive, twisted excited state accounts for these observations. Application of quantum chemical calculations to the system appears to confirm this interpretation. The fluorescence kinetics of HBT have been studied as a function of alkaline pH. Combination of the lifetime data with quantum yields and pK a* values have allowed calculation of all the rate constants in the neutral c → anion equilibrium for HBT. Similar measurements have been undertaken for substituted HBTs and for HBT at high acidities, but the data obtained has been less easy to interpret.
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2

Weragoda, Geethika K. "Excited state intramolecular proton transfer (ESIPT) and trans-cis isomerization on the triplet excited states." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439296134.

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3

Wang, Jingbo. "Non-adiabatic dynamics of excited states of molecular oxygen." Title page, contents and summary only, 1989. http://web4.library.adelaide.edu.au/theses/09PH/09phw2461.pdf.

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4

Farahani, Pooria. "Theoretical Studies of Ground and Excited State Reactivity." Doctoral thesis, Uppsala universitet, Institutionen för kemi - Ångström, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-232219.

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To exemplify how theoretical chemistry can be applied to understand ground and excited state reactivity, four different chemical reactions have been modeled. The ground state chemical reactions are the simplest models in chemistry. To begin, a route to break down halomethanes through reactions with ground state cyano radical has been selected. Efficient explorations of the potential energy surfaces for these reactions have been carried out using the artificial force induced reaction algorithm. The large number of feasible pathways for reactions of this type, up to eleven, shows that these seemingly simple reactions can be quite complex. This exploration is followed by accurate quantum dynamics with reduced dimensionality for the reaction between Cl− and PH2Cl. The dynamics indicate that increasing the dimensionality of the model to at least two dimensions is a crucial step for an accurate calculation of the rate constant. After considering multiple pathways on a single potential energy surface, various feasible pathways on multiple surfaces have been investigated. As a prototype of these reactions, the thermal decomposition of a four-membered ring peroxide compound, called 1,2-dioxetane, which is the simplest model of chemi- and bioluminescence, has been studied. A detailed description of this model at the molecular level can give rise to a unified understanding of more complex chemiluminescence mechanisms. The results provide further details on the mechanisms and allow to rationalize the high ratio of triplet to singlet dissociation products. Finally, a thermal decomposition of another dioxetane-like compound, called Dewar dioxetane, has been investigated. This study allows to understand the effect of conjugated double bonds adjacent to the dioxetane moiety in the chemiluminescence mechanism of dioxetane. Our studies illustrate that no matter how complex a system is, theoretical chemistry can give a level of insight into chemical processes that cannot be obtained from other methods.
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5

Boch, Ronald. "Development of triplet excited state probes for organized media." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/10443.

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This thesis describes the detailed evaluation of using triplet excited states of p-methoxypropiophenone derivatives to probe organized media both in the solid state and in solution. The ketone triplets decay by intramolecular charge transfer $\beta$-aryl quenching of the excited carbonyl and show a high sensitivity to conformational constraints imposed by substituents or by the surrounding environment. The experience acquired with the ketone probes proved useful also in the study of $\alpha$-terthienyl in protein environments. Preliminary experiments with chiral derivatives of these triplet ketone probes in solution, showed that methyl substitution at the $\beta$-metyhylene position (which is not a participant in the deactivation mechanism) causes a dramatic decrease in the triplet lifetime. This effect is attributed to conformational preferences imposed by the added substituents. Methyl substitution in the $\beta$-aryl ring affects the ease of oxidation of this ring and as a result induces changes in the kinetics for intramolecular charge transfer. In the solid state, X-ray structures show that the charge transfer interaction provides also an efficient mode of deactivation for the $\beta$-methylene substituted ketones but not in the unsubstituted one which crystallizes in a stretched conformation. In the case of p-methoxy-$\beta$-phenylbutyrophenone, the triplet lifetime in the solid state is 420 ns for the pure R and S enantiomers but 733 ns for the racemic crystals, showing an interesting case of chiral discrimination. Powder X-ray and solid state NMR data suggest that conformational and packing differences between the enantiomers and racemic crystals are responsible for differences in the efficiency of intramolecular deactivation. Incorporation of these probes into chiral hosts such as cyclodextrins and cholate micelles lengthen the triplet lifetimes by restricting the movement of the $\beta$-phenyl ring and thus slowing down the intramolecular deactivation process. Studies using these methyl substituted ketone probes in cyclodextrins provided information on intracavity mobility, inclusion geometries, and generally on the importance of steric factors in the formation and stability of cyclodextrin complexes. Intramolecular quenching, characteristic of these probes, provides further information on specific stereochemical constraints in CD complexes and magnifies the effects observed in homogeneous solution. Solid CD inclusion complexes were also prepared and the triplet behavior observed in the solid state was compared to solution. In anionic micelles, the ketone probes undergo two-photon photoionization under conditions of pulsed laser excitation. Both SDS and sodium cholate micelles promoted charge separation and led to hydrated electrons (e$\rm\sp-\sb{aq}$) that could be readily detected by their absorption at $\lambda > 600$ nm and through its reactions with oxygen and nitrous oxide. The lifetimes of e$\sp-\rm\sb{aq}$ were determined by small concentrations of aromatic ketone in the aqueous phase in equilibrium with the micelle solubilized ketone. The triplet behavior of $\alpha$-terthienyl photosensitizers conjugated to bovine serum albumin (BSA) was investigated. The protein conjugates were to serve as models for antibody conjugates for elucidating insect resistance to pesticides. The conjugates were prepared with varying amounts of sensitizer attached to the protein. Oxygen quenching of the conjugated $\alpha$-terthienyl triplet states is approximately an order of magnitude slower in the protein environment compared to homogeneous solution. (Abstract shortened by UMI.)
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6

Xie, Yun. "Excited-State Hydroxide Ion Transfer From A Model Xanthanol Photobase." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1430615852.

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7

Lewis, Sharlene A. "Heteroleptic dimetal quadruply bonded complexes: Synthesis, characterization and excited state properties." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406082666.

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8

Kambhampati, Patanjali. "Adsorbate-substrate charge transfer excited states /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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9

Le, Gourrierec Denis. "Excited state intramolecular proton transfer (ESIPT) to nitrogen in heterocyclic compounds." Thesis, University of Central Lancashire, 1996. http://clok.uclan.ac.uk/21906/.

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Excited state intramolecular proton transfer (ESIPT) reactions have aroused considerable interest in the last 10-15 years. The ESIPT reaction is normally extremely rapid and yields excited species of considerably lower energy than the initial Franck-Condon excited state. ESIPT has therefore been used for the rapid dissipation of energy (e. g. for polymer protection against UV degradation) and to produce fluorophores with large Stokes shifts. Approximately half of the compounds studied to date involve ESIPT to nitrogen but there has been no real attempt at a coherent study of ESIPT to nitrogen. In this work we have tried to remedy this deficiency by studying a range of compounds of increasing complexity in order to characterise ESIPT and subsequent reactions and to evaluate how these properties vary with molecular structure. The molecules selected for this studyf all into two categories: - The azole group includes the 2-(2'-hydroxyphenyl)-oxazole (HPO) and -thiazole (HPT) whose study complements their well known benzo counterparts (HPBT and HPBO) and the related imidazoles. - The compounds of the pyridine group are related to the basic structure of 2-(2'-hydroxyphenyl)-pyridine (HPP). Structural variations involve benzo fusion (quinolines) and addition of a 3,3' bridge. A complementary compound is the well studied 2,2'-bipyridyl-3,3'-diol (BP(OH)2) which undergoes double proton transfer. Whenever possible, the methoxy counterparts were prepared in order to study the photochemistry of these compounds when ESIPT is not possible. The absorption and fluorescence properties of these systems were studied as a function of solvent, temperature and pH conditions. Lifetimes, quantum yields and pKa data were determined under these various conditions and semi-empirical quantum chemical calculations were performed on each system.
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10

Stewart, Beverly. "Computational chemistry applied to the excited state decay of molecular photonic devices." Thesis, University of Newcastle Upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538922.

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11

Muro, Maria Luisa. "Platinum(II) Terpyridyls: Excited State Engineering and Solid-State Vapochromic/Vapoluminescent Materials." Bowling Green State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1242057662.

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12

Muro, Maria L. "Platinum (II) terpyridyls excited state engineering and solid-state vapochromic/vapoluminescent materials /." Bowling Green, Ohio : Bowling Green State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1242057662.

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13

Rose, Aimee 1973. "Optimizing the excited state processes of conjugated polymers for improved sensory response." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29321.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2003.
Vita.
Includes bibliographical references.
Conjugated polymers exhibit useful and interesting electrical and optical properties. We exploit the wandering excitons produced after photoexcitation for chemosensory applications. By sampling many sites in a polymer film, the excitation has a greater chance to encounter an analyte, such as 2,4,6 trinitrotoluene (TNT), electrostatically poised to induce non-radiative decay. The result is attenuation of the fluorescence signal characteristic of these bright polymers. Because energy migration is responsible for the amplification of sensory response, we sought to augment this migration by integrating chromophores with long-lived excited states into the polymer backbone. The first chromophore we targeted, triphenylene, has a symmetrically-forbidden ground state transition, resulting in a long excited state lifetime. Chapter 2 describes the synthetic incorporation of triphenylene into conjugated polymer backbones, and Chapter 3 details the spectroscopic interrogation of these materials. We demonstrate that lifetime extension is universal to all triphenylene-containing polymers. The longer excited state lifetimes are then correlated with increased energy migration through polarization spectroscopy. In Chapter 4, we extend this paradigm for elongating energy migration in conjugated polymers to several other systems. Unique polymers with symmetric, aromatic chromophores are investigated. These materials allow us to look more rigorously at the variations of effective conjugation pathways and their implications before and after chromophore cyclization. The novel dibenzo[g,p]chrysene, triphenylene and thiophene-based systems afforded us a more complete understanding of the interplay of rigidification, symmetrization, lifetime, and energy migration in conjugated polymers.
(cont.) In the final chapter, we exploit another excited state process in conjugated polymers, stimulated emission, to provide additional amplification of sensory response. We demonstrate that lasing action in optically-pumped conjugated polymer thin film structures can be inhibited by exposure of samples to trace amounts of electron deficient aromatic analytes such as TNT. Analyte exposure introduces non-radiative pathways in the polymer, increasing the lasing threshold. Because lasing is a non-linear phenomenon, it provided two orders of magnitude greater sensitivity to TNT. In combination, we hope that the developments described in this thesis will serve to improve current dernining teclmology in the near future.
by Aimee Rose.
Ph.D.
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14

Leed, Nicholas Alexander. "Photophysical Properties and Control of the Excited State of Transition Metal Complexes." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1368115489.

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15

Johnson, David G. "An investigation of excited state properties of some rhodamine dyes." Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484197.

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16

Topçu, Türker. "Time dependent studies of fundamental atomic processes in Rydberg atoms /." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Dissertations/TOPCU_TURKER_31.pdf.

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17

De, Lucia Frank Charles. "Dynamics of excited state species and morphological studies of pyridine containing conjugated polymers /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486461246816383.

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18

Tan, Xin. "Molecular reorientational relaxation and excited state dynamics probed by time-resolved fluorescence spectroscopy /." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486474078049178.

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19

Gould, Elizabeth-Ann. "The photochemistry of "super" photoacid n-methyl-6-hydroxyquinolinium and other novel photoacids." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43706.

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The photochemistry of several novel photoacids was addressed experimentally and theorectically. Initial studies focused on the excited-state proton transfer (ESPT) of several chiral phtoacids and explored the effects of chirality on ESPT; subsequent studies examined photochemistry and photophysics of "super" photoacid N-methyl-6-hydroxyquinolinium (MHQ). In the initial studies, no enantioselectivity was observed from the chiral photoacids to various chiral proton acceptors. In the later studies examining ESPT in MHQ both experimentally and theoretically, the excited-state acidity constant of the photoacid was determined to be an unprecedented -7, making it the strongest photoacid reported in the literature to-date. Consideration was then given to applications of the novel photoacid including its properties as a photoinitiator in cationic polymerizations and as a photochemical probe in gas-expanded liquids and in the Nafion membrane. In the course of these studies, an interesting fluorescence quenching effect was observed that became the subject of some exploratory studies that suggest a nucleophilic quenching mechanism.
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20

Pauszek, Raymond Francis. "Excited state charge redistribution and dynamics of flavins, flavorproteins, and their cofactors." Diss., Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/245456.

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Chemistry
Ph.D.
The excited state electronic structures of several biologically important chromophores were studied by Stark spectroscopy. The extent of charge redistribution upon excitation to the lowest excited states of the oxidized and semiquinone forms of flavin adenine dinucleotide (FAD) bound to the light activated DNA repair enzyme DNA photolyase have been studied previously by this technique. This work focuses on the catalytically active form, the two-electron reduced anion. To facilitate analysis of this experiment, the Stark spectra of a simple flavin derivative that is soluble in organic solvents was measured. The results of the analysis of these data are in agreement with previously a published linear dichroism experiment that found the absorption spectrum of flavins in this redox state arises from two distinct electonic transitions in the visible/near-ultraviolet spectral range, a fact that has not been incorporated into the analysis of many ultrafast spectroscopic experiments of reduced anionic flavins/flavoproteins. The difference dipole moment of the second, more intense, transition was found to be about twice as large as that of the lowest energy transition. With the aid of ab initio calculations, the directions of these dipole moments in the molecular frame were assigned. For both transitions, it was found that negative charge density is shifted toward the xylene ring of the flavin upon excitation. Another important consideration for the correct analysis of the photolyase spectra is the possibility of contamination by small amounts of the antenna chromophore, which also has absorption intensity in the near-ultraviolet region. We chose to study the cofactor for E. coli photolyase, 5,10-methenyltetrahydrofolate, and its photodecomposition product, 5,10-methylenetetrahydrofolate. The difference dipole moments for the lowest energy transitions of both of these chromophores were found to be quite large, ranging from 9-12 D fc and lying primarily along the transition dipole moment. Additionally, the difference polarizability of both chromophores was large, on the order of 200-300 Å3 fc2 . The Stark spectra of reduced anionic FAD in photolyase agrees well with the findings of the experiments on flavin in organic solvent; the magnitude of the difference dipole moments in both cases match within experimental error. While the direction of the difference dipole moment for the lowest transition is also the same in both cases, that of the second transition is changed in the protein matrix. The assignment of these vectors in the molecular frame shows that the two dipole moments are coincident for the cofactor bound to photolyase. This finding, where electron density is shifted toward the point of the flavin ring closes to the DNA lesion bound to the enzyme, is strong evidence that direct electron transfer takes place from the isoalloxazine ring of FAD to the DNA substrate in the catalytic cycle. The usefulness of Stark spectroscopy in investigating photoinduced charge redistribution was also shown for the donor-π-acceptor flavin dyad, azobenzylflavin (ABFL). The difference dipole moment was found to be 22 D, an approximately three-fold increase from the largest difference dipole moment found in naturally occurring flavins. This extensive charge redistribution corresponds to a large hyperpolarizability of the chromophore that suggests that ABFL may be useful in nonlinear optical applications. Transient absorption was used to supplement these experiments by monitoring the decay kinetics of ABFL after excitation. It was found that ABFL undergoes ultrafast charge recombination within 6 ps after excitation, leading to depopulation of the charge separated state before useful work can be performed for applications requiring electron transfer. These studies provide the ground work for rational design of other ABFL-like derivatives for use in a variety of applications.
Temple University--Theses
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21

Kotani, Ryota. "Chemistry on Flapping Fluorophores That Bridges Photochemistry and Polymer Mechanochemistry." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263486.

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22

Barnes, Peter William. "An investigation into the state selective chemistry of vibrationally excited water with hydrogen atoms." Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369757.

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23

Drummond, Michael L. "Denisty functional theory investigations of the ground- and excited-state chemistry of dinuclear organometallic carbonyls." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1104284754.

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24

Zhou, Dapeng. "The Excited State Behavior of Iminium Derivatives and Their Reduced Forms." Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1370525481.

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25

Hare, Patrick Michael. "Excited state dynamics in DNA base monomers the effects of solvent and chemical modification on ultrafast internal conversion /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1166623261.

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26

Jacobsen, Ruth L. "Ab initio configuration interaction (CI) calculation of the charge-density susceptibility of molecular hydrogen and higher-order Van der Waals interactions from perturbation theory." Diss., Connect to online resource - MSU authorized users, 2006.

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27

Drummond, Michael Lee. "Density functional theory investigations of the ground- and excited-state chemistry of dinuclear organometallic carbonyls." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1104284754.

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Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xxi, 298 p.; also includes graphics. Includes bibliographical references (p. 280-298).
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28

Xue, Congcong. "The Excited State Properties of Dirhodium (II,II) Complexes: Application for Solar Energy Conversion." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565632080675563.

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29

Parker, A. W. "Excited state studies of pyrimidine bases and radiosensitizing drugs by laser flash photolysis." Thesis, University of Warwick, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377105.

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30

Kender, William Theodore. "Controlling Excited State Electron Delocalization via Subtle Changes to Inorganic Molecular Structures." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534271989190317.

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31

Ziehm, Christopher. "Ground State and Excited State Mixed Valency in Metal-Metal Quadruply Bonded Complexes Supported by Extended π Ligands." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469017749.

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32

Barnard, David Thomas. "EXCITED STATE DYNAMICS AND CHARGE REDISTRIBUTION OF EXTREMOPHILE DNA PHOTOLYASE AND FLAVIN COFACTORS." Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/597264.

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Chemistry
Ph.D.
Repair mechanisms for damaged DNA are essential for the proliferation of nearly all forms of life. Although DNA is quite robust, the vital information-storing molecule can often be damaged from environmental exposures such as ultra-violet (UV) light. Exposure to UV light can result in various types of mutagens creating structural damages. One specific type of UV-induced damage is the creation of a cyclobutylpyrimidine dimer (CPD). This specific type of lesion can be efficiently repaired by the flavoenzyme DNA photolyase (PL). DNA photolyase is an ancient protein found across kingdoms and plays a crucial role in preventing mutagenesis and cell death. DNA photolyase is a monomeric flavoprotein that utilizes blue light to repair UV-induced CPD lesions in DNA via an electron transfer mechanism. All photolyases contain at least one flavin adenine dinucleotide (FAD) molecule as the catalytic cofactor responsible for initiating the electron transfer induced repair process. Flavin cofactors are intriguing because of their unique ability to donate one or two electrons. The conservation of FAD and the unique U-shaped configuration of FAD in PL led researchers to question if the adenine moiety of the FAD molecule was essential in the DNA repair mechanism and generated a spectral signature indicative of a radical adenine species. The importance of the adenine moiety could be linked to structural changes associated with environmental temperature. The rate of electron transfer is exponentially dependent on temperature and DNA photolyase is found in organisms which thrive in harsh environments that vary in temperature, pH, ionic strength etc. Photolyase presents a unique opportunity to study the adaptations that are required for proteins to function in extreme environments where temperature dependent processes should show dramatic differences. We have used ultrafast transient absorption spectroscopy to compare the similarities and differences in excited state dynamics of the FAD cofactor. Photolyase isolated from the hyperthermophilic archaea Sulfolobus solfataricus (SsPL) is compared to PL isolated from the mesophilic E. coli (EcPL). These results indicate differences in the dynamics of fully reduced flavin between enzymes as a function of temperature. We present evidence for charge separation in the FAD cofactor in the thermophilic enzyme previously seen in computation studies of photolyase. To investigate the excited state charge redistribution of flavin which is critical to its role in nature, the charge redistribution of the precursors to flavin biosynthesis were examined. Lumazine is a precursor in the biosynthetic pathway of flavins. As such, lumazine could have served as an enzymatic cofactor prior to flavins. Lumazine has been identified in biological processes, however it is not as prevalent as flavins. We utilize Stark spectroscopy to examine the charge redistribution in excited state lumazine to understand
Temple University--Theses
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33

Richings, Gareth William. "New methods in quantum chemistry : single determinant approximations to post-Hartree-Fock and excited state wavefunctions." Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440869.

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34

Kandappa, Sunil Kumar. "Light as a Reagent for Chemical Reactions-Excited State Manipulation to Discover New Reactivity." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1573830383912829.

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35

Chen, Ling. "Improvements in excitation selectivity and spectral precision in Fourier transform NMR and mass spectrometry /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487330761219982.

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36

Morrison, Adrian Franklin. "An Efficient Method for Computing Excited State Properties of Extended Molecular Aggregates Based on an Ab-Initio Exciton Model." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1509730158943602.

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37

Kodali, Goutham. "Excited state electronic properties of DNA photolyase and fluorescent nucleobase analogues (FBA): An experimental and theoretical study." Diss., Temple University Libraries, 2009. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/58803.

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Abstract:
Chemistry
Ph.D.
An overexposure to ultraviolet radiation can cause sunburn and some forms of skin cancer. UV light causes many different photoproducts. The cys-syn cyclobutylpyrimidine dimer (CPD) is the major photoproduct upon UV irradiation. DNA photolyase (PL) is a light-driven flavoprotein that repairs CPD in UV-damaged DNA. This repair process occurs in the presence of blue light through ultrafast photo-induced electron transfer from reduced anionic flavin adenine dinucleotide (FADH¯) to the CPD by an unknown mechanism. Since the excited state flavin transfers an electron to repair the damaged DNA, it is of utmost importance that we understand better the excited state properties of the flavins. In this work the excited state electronic properties of all three-oxidation states of flavin: oxidized form (FAD), semiquinone radical form (FADH•) and reduced anionic form (FADH¯) were studied using Stark spectroscopy and complimented by time dependent density functional theory (TD-DFT) calculations. These results are presented and discussed in Chapter 3 and 4. The difference dipole moments (Δμ) and the difference polarizabilities (Tr(Δα01)) were experimentally determined for first two lowest optically accessible states. The results are discussed in the context of photoreduction of flavins in wider class of flavoprotein blue light photoreceptors and catalytic electron transfer process in DNA repair. In the later part of this thesis (Chapters 5 and 6) the excited state electronic properties of monomeric 2-Aminopurine (2AP), 8-Vinyladenine 8VA were presented. These 8VA, 2AP are examples of fluorescent nucleotide analogues of adenine that can be incorporated into DNA with little perturbation of the normal double-helical structure. The fluorescence of these analogues is quenched when incorporated in double-stranded DNA (dsDNA). The basic mechanism underlying the fluorescence quenching by base stacking of 2AP and 8VA are is not well understood, and thus exploring the excited state electronic structures of these bases is an important first step. We have explored the excited state properties of 2AP and 8VA in frozen LiCl and ethanol solutions using Stark spectroscopy. High-level ab initio and TD-DFT calculations were performed to compliment the experimental results.
Temple University--Theses
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38

Shand, Mark Alexander. "Excited state processes of complexes of W(V) and U(VI) by laser photolysis and ESR spectroscopy." Thesis, University of Warwick, 1987. http://wrap.warwick.ac.uk/34627/.

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This thesis deals with the reactions of two high-valent metal complexes. [UO2]2+ and [W(CN)8]3- in their excited states in which their one-electron reduction potentials are increased greatly, i.e. sufficiently for them to remove an electron from water. The studies with uranyl ion cover the following, (i) the ground state interaction with some simple amino acids, (ii) the excited-state interaction with a variety of amino acids including some containing sulphur, which gave results of particular interest and, in following up the latter, (iii) the excited state interaction with some simple organosulphur compounds. These three inter-related topics form Chapters 8, 9 and 10 of this thesis. In more detail, in Chapter 8 we characterise optically, three new complexes of 1:4 stoichiometry between [UO2]2+ and glycine and α- and β-alanine in acidic aqueous solution. The x-ray crystal structure of the glycine complex confirms it as tetrakis (glycine) dioxouranium (VI) nitrate. Chapter 9 covers the kinetics of luminescence quenching of *[U02]2+ by amino acids (indicating the level of reactivity) and the quant yields of [U(IV)] which indicate the degree of charge separation from the initial radical-pair configuration, while cryogenic ESR data reveal the nature of the primary ligand-derived radical. Interestingly we find that while much the greatest kinetic reactivity towards *[UO2]2+ is shown by the sulphur-containing amino acids, these show very low yields for [U(IV)] production. This pattern is repeated in our study of the photo-oxidation of dialkyl sulphides by excited uranyl ion, in which we believe to have demonstrated that a. recent report of high quantum yields in this system and published in Inorganic Chemistry is erroneous. Our brief study of the aqueous [W(CN)8]3- system confirms the quantum yields for [W(CN)8]4- of Samotus et al., as opposed to the earlier data of Balzani and Carassiti and characterises, using ESR, IR and UV-vis spectroscopy, new W(V)-cyanide 4 complexes obtained during irradiation into the C-T bands of [W(CN)8]4- and [W(CN)8]3- in aqueous solution. Three publications have resulted hitherto from the above work in the following journals: Chapter 8: J. Chem. Soc., Dalton Trans., 1985, 517. Chapter 9:, Inorgý Chim. Acta, 1986, 114, 215. Chapter 10: Inorg. Chem., 1986, 21, 3840. The results from the final chapter together with data from the photoreduction of [W(CN)8]3- 81 with many organic systems obtained by Dr. D. Rehorek during his visit to the Department, have been compiled and submitted for publication to the Journal of the Chemistry Society, Dalton Transactions (paper 6/2444).
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39

Glik, Elena A. "Spectroscopic Investigation of the Excited State Properties of Platinum(Ii) Charge Transfer Chromophores." Bowling Green, Ohio : Bowling Green State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1256141493.

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40

Wang, Lei. "Ultrafast Excited State Investigation of Ruthenium and Osmium Polypyridyl SulfoxideComplexes and BOPHY Dyes." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1433864223.

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41

Abrahamsson, Maria. "Tuning of the Excited State Properties of Ruthenium(II)-Polypyridyl Complexes." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7230.

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42

Loftus, Lauren Marie. "Tuning the Excited States and Reactivity of Polypyridyl Ru(II) Complexes for Photochemotherapy." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu156579728991504.

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43

Campos, Ramos Ricardo E. "STRUCTURE AND EXCITED-STATE DYNAMICS OF AROMATIC NITRILES IN SUPERSONIC FREE JET." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1132244275.

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44

Stedl, Todd Robert. "Computational investigations of the dynamics of chlorine dioxide /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/8497.

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45

Thibodeau, Daniele L. Carleton University Dissertation Chemistry. "Resonance raman excitation study of monomeric and dimeric chlorophyll a in solution." Ottawa, 1988.

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46

Okhrimenko, Albert N. "ULTRAFAST EXCITED STATE RELAXATION DYNAMICS OF ELECTRON DEFICIENT PORPHYRINS: CONFORMATIONAL AND ELECTRONIC FACTORS." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1126888140.

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47

Albani, Bryan A. "Control of Excited States and Photoinduced Ligand Substitution Reactions in Ru(II) Complexes for Photochemotherapy." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429620404.

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48

Chen, Weihua. "Chemical Sensors Based on Fluorescence Turn-On Mechanism by Using Excited State Intramolecular Proton Transfer." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1334772708.

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49

Law, Yu Kay. "Relationship Between the Kinetics of Thymine Dimer Formation and the Excited State Dynamics of DNA." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1276861431.

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50

Khajehpour, Mazdak. "Solvent effects upon the charge-transfer reaction of the ADMA molecule in the excited state /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3025621.

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