This work covers spectroscopic studies of nuclei from different regions of the Segré chart whose properties illustrate the delicate balance between the forces in the atomic nucleus. Studies of nuclei far from stability offer new insights into the complex nucleon many-body problem. In nuclei with equal neutron and proton numbers (N = Z), the unique nature of the atomic nucleus as an object composed of two distinct types of fermions can be expressed as enhanced correlations arising between neutrons and protons occupying orbitals with the same quantum numbers. The bound N = Z nuclei with mass number A &gt; 90 can only be produced in the laboratory at very low cross sections. The related problems of identifying and distinguishing such reaction products and their associated gamma rays have prevented a firm interpretation of their structure even for the lowest excited states until recently. In the present work the experimental difficulties of observation of excited states in the N = Z = 46 nucleus 92Pd have been overcome through the use of a highly efficient, state-of-the-art detector system; the EXOGAM-Neutron Wall-DIAMANT setup, and a prolonged experimental running period. The level spacings in the ground state band of 92Pd give the first experimental evidence for a new spin-aligned neutron-proton (np) paired phase, an unexpected effect of enhanced np correlations for N = Z nuclei in the immediate vicinity of the doubly magic nucleus 100Sn. Excited states in 94Ru and 95Rh nuclei close to the double magic shell  Z = N = 50 have been studied in order to untangle the ambiguity of the spin and the parity of the lowest-lying states. The observed yrast structures are compared to results of large-scale shell model (LSSM) calculations and the strengths of hindered E1 transitions are used as a sensitive test of the LSSM parameters. The effect of single-particle-hole excitations is discussed in terms of the strength of hindered E1 transitions. Excited states of the odd-odd nucleus 162Ta have been observed using the JUROGAM/RITU experimental set-up. This nucleus is located in a transitional region in the nuclide chart which is between near-spherical nuclei and well-deformed nuclei, offering the possibility to study the emergence of collective phenomena and nuclear deformation (in particular the degree of triaxiality). The results, which are interpreted in the framework of the cranked shell model with total Routhian surface calculations, suggest an almost axially symmetric nuclear shape. The energy staggering between the signature partners of the yrast rotational bands has been deduced for eight odd-odd isotopes in the neighborhood of 162Ta nucleus and the special observed feature of signature inversion for these nuclei is discussed. / <p>QC 20140217</p>

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This thesis presents a spectroscopic and computational study of a variety of substituted oligothiophenes. The purpose of this study was to elucidate the structural properties of their neutral, oxidised and excited states. This was accomplished using a number of spectroscopic methods, including electronic absorption, resonance Raman and fluorescence spectroscopy. Analysis of the data provided by these methods was aided by the application of density functional theory (DFT) to the neutral and charged species, allowing conclusions regarding bond length changes and molecular orbitals to be drawn. Advancing the understanding of the structural properties of conductive materials such as oligothiophenes is important due to their potential application in plastic electronic devices (organic solar cells, field effect transistors and light emitting diodes, for instance) and the need to clarify the charge transport mechanism. The compounds examined in this thesis are primarily based on 3� styryl-substituted terthiophene. Substituted derivatives of this molecule include those with groups on the para position of the phenyl ring or methyl α,α� end caps. Larger ethenyl-aryl groups were also investigated, as were analogous thiophenes and sexithiophenes. Indeed, the 3�-substituted sexithiophenes formed an integral part of this investigation since they rapidly form in the head-to-head orientation from the oxidation and consequent [sigma]-dimerisation of the substituted terthiophenes. DFT calculations on the sexithiophene charged species have indicated the presence of a full polaronic or bipolaronic structural defect in the centre of the thiophene backbone, as defined by the reversal of the CC bond length alternation to create a domain of quinoidal bond sequence. However, the structural defect of the styryl sexithiophenes is more strongly localised than that observed for unsubstituted sexithiophene; indeed, the charged defect appears to be confined by the positions of the styryl substituents. This defect confinement along the thiophene backbone is particularly apparent in the styryl sexithiophene dications. Electronic absorption and resonance Raman spectroscopy have been applied to the oxidation products of the styryl terthiophenes. Only sexithiophene charged species are observed when the α termini are unsubstituted; these include sexithiophene radical cations, [pi]-dimers (a stabilising face-to-face interaction between two radical cations) and dications. The resonance Raman spectra of these charged species are characterised by a very intense symmetrical CC stretching mode of the thiophene inter-ring bonds, which is also evident in the theoretical spectra. The extensive differences between the styryl and unsubstituted sexithiophene dication Raman spectra have been attributed to defect confinement: the strongest Raman band of the unsubstituted sexithiophene dication is due to a vibrational mode localised over the entire sexithiophene backbone while that of the styryl sexithiophenes is localised over the central two thiophene rings - the same area occupied by the confined defect. A combined steady-state and picosecond time-resolved emission study on the styryl terthiophenes revealed that by judicious choice of the para R group in styryl terthiophenes it is possible to tune the nature of the first excited singlet state from [pi],[pi]* to charge transfer character. Charge transfer states may offer possible strategies for solar cells in which charge separation is a key step.

Thesis (PH.D.) -- Syracuse University, 2007. / "Publication number AAT 3266308"

Thesis--Wisconsin. / Includes bibliographical references (leaves 94-99).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1931. / Typescript. With this are bound: The dielectric constants of binary mixtures : IX. The electric moments of certain substituted phenols and their relation to the stereochemistry of the oxygen atom / By John Warren Williams and John M. Fogelberg. Reprinted from Journal of the American Chemical Society, vol. 52 (1930), p. 1356-1363 -- Die Anwendung der Debyeschen Dipoltheorie auf binäre Flüssigkeitsgemische : III. Derivative des Ammoniaks / Von John M. Fogelberg und John Warren Williams. "Sonderdruck aus 'Physikalische Zeitschrift', 32. Jahrg., 1931, Heft I, S. 27-31." Includes bibliographical references (leaves 43-44).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 347-357).

Thesis--Wisconsin. / Vita. Includes bibliographical references.

Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographies.

Texte remanié de: Th. Ph. D.--University of Dehli, 1965. / Bibliogr. p. 226-228. Index.