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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.
111

The structure and dynamics of liquid semiconductors and superionic conductors by neutron scattering

Hamilton, Myles January 2000 (has links)
No description available.
112

Modifying thin film diamond for electronic applications

Baral, Bhaswar January 1999 (has links)
No description available.
113

Powder X-ray diffraction studies of structural and kinetic aspects of polymorphism

Chan, Fung Choy January 1999 (has links)
No description available.
114

Transparent, rare earth doped, oxyfluoride glass-ceramics for photonics

Kukkonen, Liv Linnea January 2000 (has links)
No description available.
115

Synthesis and complexation of acyclic dithiolate ligands

Ashford, Lynette January 1999 (has links)
No description available.
116

A study of defects in diamond

Hunt, Damian January 1999 (has links)
No description available.
117

Liquid crystals with novel terminal chains as ferroelectric liquid crystal hosts

Cosquer, Guirec Yann January 2000 (has links)
No description available.
118

Electrical and magnetic properties of organic semiconductors : electrical conductivity and electron spin resonance studies of semiconducting, organic, charge transfer salts

Ahmad, Muhammad Munir January 1978 (has links)
Charge transfer salts of Tetracyanoquinodimethane (TCNQ) were synthesised and their electrical and magnetic properties were investigated. These salts show unusual electrical and magnetic behaviour in contrast to conventional organic compounds. These salts have crystal structures which in general consist of TCNQ radical ions stacked in chains, isolated from each other by the diamagnetic cations. They are thus regarded as "one-dimensional" electrical and magnetic systems. The ESR spectra of these salts are attributed to triplet excitons showing that the spin-spin and electronelectron correlation effects are important. In the ESR spectra (Chapter III) of some TCNQ salts dipolar splitting is observed confirming the spin-spin interaction. These triplet excitons are regarded as bound electron-hole pairs. The experimentally determined dipolar splitting tensors are presented in Chapter III and the intensity data in Chapter IV. A large number of fine structure lines are observed in the ESR spectra of Pyridinium-TCNQ and 4-Aminopyridinium-TCNQ apart from regular triplet exciton lines (Chapter III). These lines are attributed to the trapping of excitons on an extended formula finit (TCNQ2 )n. In Chapter IV the temperature dependent magnetic susceptibilities are discussed in terms of Heisenberg antiferromagnetism and Pauli paramagnetism. In Chapter V temperature dependent behaviour of electrical conductivity is discussed in terms of an exciton band model, the lattice structure of the salts and one-dimensional lattice consisting of defects giving rise to high and low conducting segments. Low temperature electrical and magnetic phases are discussed (Chapters IV and VII) in terms of a band and hopping mechanisms.In Chapter VI self consistent field calculations are made with reference to the tight binding one electron band theory using simplified Roothaan equations considering CNDO approximations. Theoretical results are related to experimental band gaps, spinspin interactions and charge alteration.
119

Effect of low-temperature argon matrices on the IR spectra and structure of flexible N-acetylglycine molecules

Stepanian, S. G., Ivanov, A. Yu., Adamowicz, L. 12 1900 (has links)
A study of how the matrix environment impacts the structure and IR spectra of N-acetylglycine conformers. The conformational composition of this compound is determined according to an analysis of the FTIR spectra of N-acetylglycine isolated in low temperature argon matrices. Bands of three N-acetylglycine conformers are identified based on the spectra: one major and two minor. The structure of all observed conformers is stabilized by different intramolecular hydrogen bonds. The Gibbs free energies of the conformers were calculated (CCSD(T)/CBS method), and these energy values were used to calculate conformer population at a temperature of 360 K, of which 85.3% belonged to the main conformer, and 9.6% and 5.1% to the minor conformers. We also determined the size and shape of the cavities that form when the N-acetylglycine conformers are embedded in the argon crystal during matrix deposition. It is established that the most energetically favorable cavity for the planar main conformer is the cavity that forms when 7 argon atoms are replaced. At the same time, bulky minor conformers were embedded into cavities that correspond to 8 removed argon atoms. We calculated the complexation energy between argon clusters and conformers, and the deformation energy of the argon crystal and the N-acetylglycine conformers. The matrix-induced shifts to the conformer oscillation frequency are calculated. Published by AIP Publishing.
120

Probing the spin-orbit Mott state in Sr3Ir2O7 by electron doping

Hogan, Thomas C. January 2016 (has links)
Thesis advisor: Stephen D. Wilson / Iridium-based members of the Ruddlesden-Popper family of oxide compounds are characterized by a unique combination of energetically comparable effects: crystal-field splitting, spin-orbit coupling, and electron-electron interactions are all present, and the combine to produce a Jeff = 1/2 ground state. In the bilayer member of this series, Sr3Ir2O7, this state manifests as electrically insulating, with unpaired Ir4+ spins aligned along the long axis of the unit cell to produce a G-type antiferromagnet with an ordered moment of 0.36 uB. In this work, this Mott state is destabilized by electron doping via La3+ substitution on the Sr-site to produce (Sr1−x Lax)3Ir2O7. The introduction of carriers initially causes nano-scale phase-separated regions to develop before driving a global insulator-to-metal transition at x=0.04. Coinciding with this transition is the disappearance of evidence of magnetic order in the system in either bulk magnetization or magnetic scattering experiments. The doping also enhances a structural order parameter observed in the parent compound at forbidden reciprocal lattice vectors. A more complete structural solution is proposed to account for this previously unresolved distortion, and also offers an explanation as to the anomalous net ferromagnetism seen prior in bulk measurements. Finally, spin dynamics are probed via a resonant x-ray technique to reveal evidence of spin-dimer-like behavior dominated by inter-plane interactions. This result supports a bond-operator treatment of the interaction Hamiltonian, and also explains the doping dependence of high temperature magnetic susceptibility. / Thesis (PhD) — Boston College, 2016. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

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