Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 45 for “"Singlet state"”.
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Density functional theory study of the conductivity of the biphenalenyl radical dimer
… the spiro-biphenalenyl neurtral radical in its singlet and triplet states. We performed calculations on the dimer to study its conductivity by investigating the ground state energy, HOMO-LUMO gap, charge localization, and reorganization energies, as these are the main contributing factors to …
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Preserving hyperpolarised nuclear spin order to study cancer metabolism
… might be accessible by using the nuclear singlet configuration of two coupled nuclei. The singlet state is immune to intramolecular dipole-dipole relaxation processes, which is one of the main sources of signal decay in MRI. In favourable situations, the singlet relaxation time constant …
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Laser-Induced Fluorescence Studies of Molecular Dynamics
… pentanedione have been recorded for the excited singlet state of each molecule. In particular, the fluorescence of biacetyl in a molecular beam has been shown to exhibit the quantum beat effect in the time-resolved fluoresence. By the use of a simple, perturbation theory-derived analysis and also …
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Part One: Photochemistry of Aryl Azides. Chemical Properties of the Transient Intermediates. Part Two: Thermolysis of an Endoperoxide. Generation of an O-Xylylene Peroxide (Nitrene)
… aryl nitrenes, with relatively long-lived singlet-state precursors. The structures of these intermediates and their rates of reaction with secondary amines are discussed.
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DIARYL NITRENIUM IONS: ELECTRONIC STATE REACTIONS, MECHANISTIC STUDIES, AND PEPTIDE LABELING
… nitrenium ion 2 raises the triplet state energy by approximately 8 kcal/mol, it’s singlet state reaction rates are only minorly decreased. Chapter 3 investigates diaryl nitrenium ions’ mechanism with H-atom donors as the parent amine has been reported in the literature as evidence of …
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Computation of Phosphorus-31 NMR chemical shifts of nickel complexes using density functional theory
… Single point energy calculations show the singlet state to be lower in energy for all nickel(II) complexes under investigation. The singlet state nickel(II) complexes were screened for multireference character by examining Etriplet – Esinglet (ΔE) and the HOMO-LUMO energy gap as recommended …
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Experimental methods to examine the role of vibrational excitation in the singlet-triplet spin-orbit coupling in acetylene
… coupling mechanism where the first excited singlet state S couples to the triplet state T3 which is then coupled to the dense manifold of vibrational states in the T, 2 electronic states. A description of theories imperative to this study is provided and each is related to its application in …
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Photolysis of (Halomethyl)naphthalenes: An Investigation of the Heterolysis and Homolysis of Carbon-Halogen Bonds in (Arylmethyl)halides
… cleavage. The first originates from an excited singlet state, and may be direct or may involve an exciplex formed during sensitization. The second mode is through an exciplex of the (halomethyl)naphthalene and a triplet sensitizer. The third mode appears to be important only for …
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Sixteen valence-electron species containing boron: structural diversity abounds
… connectivities have been examined for the singlet state. Chemical intuition suggests a ketene-like structure for each system, with the general form H₂XBY, where X = C or N and Y = F or O. The calculations yield a variety of possible structures for these species, including both cyclic and …
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High Pressure Study of Viscosity Effects on the Luminescence of Some S-Tetracyanobenzene Eda Complexes
… by emission from the equilibrium (EQ) excited singlet state to one dominated by Franck-Condon (FC) singlet emission. Lifetime measurements for the complexes of o-xylene and p-xylene with TCNB yielded the two radiative rates (k(,EQ) and k(,FC)) as well as the rate of relaxation from FC to the EQ …
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Quantum Beat Spectroscopy and Radiationless Transitions
… concerning the density of interacting states and the average intramolecular coupling energies. The simpler beat patterns can be analyzed using a perturbation theory approach and the more complex beat patterns of biacetyl were analyzed using a method based on the properties of random …
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Singlet Oxygen Generation Via Irradiation of 4-Benzylamino-7-Nitrobenz-2-Oxa-1, 3-Diazole
… (BBD) generates the first excited singlet state of molecular oxygen in liquid solution. The problem was first approached using the sensitized photooxidation method of singlet oxygen detection with 1, 3-cyclohexadiene (CHD) as acceptor. A reaction between BBD and the acceptor …
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ΕΝΔΟΜΟΡΙΑΚΗ ΦΩΤΟΚΥΚΛΟΠΟΙΗΣΗ ΤΗΣ ΚΑΡΒΟΝΗΣ ΠΡΟΣ ΚΑΡΒΟΝΟΚΑΜΦΟΡΑ
… 0. 0088IN ETOH. INVOLVEMENT OF DIFFERENT EXCITED STATES IS SUGGESTED FOR THE PHOTOCYCLIZATION OF CARVONE IN NON POLAR (A TRIPLET STATE) AND IN HYDROXYLIC SOLVENTS (N,N* SINGLET STATE) ON THE BASIS OF THE RESULTS AND THE EFFECT OF WATER ON THE ABSORPTION SPECTRUM OF CARVONE. THE INTRAMOLECULAR …
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A Study of Reactive Intermediates Generated by One-Electron Transfers (Diazoalkane, Cieel, Chemiluminescence, Carbene, Peroxide)
… Electro-transfer quenching of the excited singlet state of 1,4-dicyanonaphthalene (DCN) by 1 was found by nanosecond transient absorption spectroscopy to generate DCN('-) and another short-lived species whose (lamda)(,max) occurs at ca. 520 nm. This absorption is tentatively assigned to …
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Quantum State Singlet-Triplet Character Control in 7Li2
… levels (the G1Πg (12, 21f) and 13Sg- (1, 21f) states separated by 720 MHz). In the absence of any optical fields, the spin-orbit interaction couples the two states, resulting in each state being a mixture of the pure singlet and pure triplet states. The initial mixing coefficients are governed …
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Theoretical Investigation of the structures and stability of gas phase neutral and cationic TixOy clusters.
… the neutral clusters are usually found in the singlet state. Generally, in bulk and in the case of the neutral TixOy clusters, the 2x cluster series is relatively more abundant than the 2x-1 and the 2x+1 cluster series. But in the case of cationic TixOy clusters, the 2x-1 series is more …
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Quantum saturation and condensation of excitons in copper (I) oxide
… and interconversion between ortho (triplet-state) and para (singlet-state) excitons, using parameters for the excitonic decay, the coupling to acoustic and low-lying optical phonons, Auger recombination, and ortho-para interconversion derived from experiment. The single adjustable parameter …
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Spectroscopic signatures of doorway-mediated intersystem crossing
… is described by a doorway-mediated model, where singlet-triplet mixing between the first excited singlet~ state, S₁, and the manifold of low-lying T₁,₂ states is controlled by special vibrational levels of the third excited triplet state, T₃. However, the influence of T₃ doorway states on the …
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Investigation of the Photophysical Properties of pi-Conjugated Polymers. A Study by Non-Linear, Time-Resolved, and Single-Molecule Spectroscopy
… functions of the lowest electronically excited singlet states were studied. It was found that the symmetry selection rules for optical transitions are rather strictly fulfilled, demonstrating the high intra-chain order in MeLPPP. Additionally, these data gave evidence that the energies of the …
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Optical spectroscopy of single-walled carbon nanotubes in high magnetic fields
… predictions. Recent theory predicts a dark singlet exciton state (below the only bright singlet state) which brightens as B is applied. Our observation of two bright excitons at high B demonstrates that magnetic field is indeed capable of brightening dark excitons.
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