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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Electric dipole moments, cluster metallicity, and the magnetism of rare earth clusters

Bowlan, John 06 July 2010 (has links)
One of the fundamental properties of bulk metals is the cancellation of electric fields. The free charges inside of a metal will move until they find an arrangement where the internal electric field is zero. This implies that the electric dipole moment of a metal particle should be exactly zero, because an electric dipole moment requires a net separation of charge and thus a nonzero internal electric field. This thesis is an experimental study to see if this property continues to hold for tiny sub- nanometer metal particles called clusters (2 - 200 atom, R < 1 nm). We have measured the electric dipole moments of metal clusters made from 15 pure elements using a molecular beam electric deflection technique. We find that the observed dipole moments vary a great deal across the periodic table. Alkali metals have zero dipole moments, while transition metals and lanthanides all have dipole moments which are highly size dependent. In most cases, the measured dipole moments are independent of temperature (T = 20 - 50 K), and when there is a strong temperature dependence this suggests that there is a new state of matter present. Our interpretation of these results are that those clusters which have a non- zero dipole moment are non-metallic, in the sense that their electrons must be localized and prevented from moving to screen the internal field associated with a permanent dipole moment. This interpretation gives insight to several related phenomena and applications. We briefly discuss an example cluster system RhN where the measured electric dipole moments appear to be correlated with a the N2O reactivity. Finally, we discuss a series of magnetic deflection experiments on lanthanide clusters (Pr, Ho, Tb, and Tm). The magnetic response of these clusters is very complex and highly sensitive to size and temperature. We find that PrN (which is non-magnetic in the bulk) becomes magnetic in clusters and TmN clusters have magnetic moments lower than the atomic value as well as the bulk saturation value implying that the magnetic order in the cluster involves non-collinear or antiferromagnetic order. HoN and TbN show very similar size dependent trends suggesting that these clusters have similar structures.
32

Studies on the conformational behaviour of x, w-amino acids in aqueous solution.

Job, John Leonard January 1973 (has links)
No description available.
33

Neutron electric dipole moment from QCD sum rules /

Chan, Chuan-Tsung, January 1996 (has links)
Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [114]-116).
34

Novel concepts in the design and synthesis of organic nonlinear optical and electro-optic materials /

Bhattacharjee, Sanchali. January 2006 (has links)
Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 169-180).
35

Theoretical studies of atom-atom, atom-photon and photon-photon entanglement

Sun, Bo. January 2006 (has links)
Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2007. / You Li, Committee Chair ; Citrin David, Committee Member ; Kuzmich Alex, Committee Member ; Fox Ronald, Committee Member ; Chapman Michael, Committee Member.
36

Microscopy studies of non-linear optical materials /

Wallace, Paul M., January 2005 (has links)
Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 127-132).
37

Computerized method for finding the ideal patient-specific location to place an equivalent electric dipole to derive an estimation of the electrical activity of the heart

Sevilla, David. January 2007 (has links)
Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.
38

Development of a SQUID magnetometry system for a cryogenic neutron electric dipole moment experiment

Cottle, Amy January 2015 (has links)
No description available.
39

Dipole Moments of Diphenyl Compounds with Conjugated Double Bonds

Spalding, Dan W. January 1950 (has links)
This thesis is a continuation of a study of molecular moments begun by Joseph T. Fielder. In his paper he discussed the theory and the equipment necessary for such a study. It is the purpose of this paper to set forth modifications of his equipment, to present data obtained with this modified equipment, and to interpret this data.
40

Nuclear Schiff Moment Search in Thallium Fluoride Molecular Beam: Rotational Cooling

Wenz, Konrad January 2021 (has links)
The search for physics beyond the Standard Model has been a main focus of the scientific community for several decades. Unknown physics in the form of new interactions violating the simultaneous reversal of charge and parity symmetries (CP) would, for example, provide a significant step towards understanding the baryon matter-antimatter asymmetry observed in the Universe. Such parameters are predicted to also manifest themselves in atomic and molecular systems in the form of both: permanent electric dipole moments and nuclear charge distribution asymmetries described by the nuclear Schiff moment. Both can be measured to a high degree of precision in modern experiments, allowing us to place stringent limits on parameters appearing in new fundamental theories. The Cold Molecule Nuclear Time Reversal Experiment (CeNTREX) is the latest approach to probing these effects. CeNTREX is a molecular beam experiment that uses thallium fluoride (²⁰⁵Tl⁹F) as its test species to measure energy shifts induced by the interaction of thallium's nuclear Schiff moment. It does so by performing nuclear magnetic resonance using a separate oscillatory fields technique. The precision of this measurement is dictated by the free precession time and the number of interrogated molecules, and is significantly enhanced by thallium fluoride's inherent properties. Employing novel methods, CeNTREX strives to achieve significant improvements to limits placed on the fundamental parameters. One such method is rotational cooling. It was thoroughly analyzed, simulated and experimentally confirmed - with the help of optical and microwave pumping, we collapsed the initial Boltzmann distribution of molecules amongst their rotational states into one chosen hyperfine state of the ground rotational state manifold. The efficiency of this process depends on multiple factors, the most crucial being the approach towards dark state destabilization and remixing. After careful investigation, we chose the most appropriate method and devised an efficient rotational cooling scheme. Experimental confirmation showed an enhancement factor of r𝑓23.70±1.13, very close to our theoretical predictions. This allows us to conclude that CeNTREX should provide a 2500-fold improvement over the current best measurements of the nuclear Schiff moment in thallium nucleus.

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