Thesis (Ph. D.)--University of Wisconsin--Madison, 1985. / Typescript. Vita. Includes bibliographical references (leaves 268-283).

[No abstract available] / Science, Faculty of / Physics and Astronomy, Department of / Graduate

A comparative study has been made of Penning ionization (He*(2¹S) and He*(2³S)) and photoionization (He(584 Å)) of twenty-three atoms and molecules (Ar, Kr, Xe, H₂, HD, D₂, N₂, CO, NO, 0₂, C0₂, COS, CS₂, N₂0, S0₂, N0₂, NH₃, CH₃CI, CH₃Br, CH₃I, CH₄, C₂H₄ , C₂H₂) employing the techniques of high resolution electron spectroscopy. Electron spectra from mixed rare gas systems, at higher pressures, have also been examined and interpreted on the basis of fast neutral-neutral interactions. / Science, Faculty of / Chemistry, Department of / Graduate

Energy loss spectra of 2.5 keV electrons, scattered by molecular targets through small angles, have been studied in the regions of the respective carbon, nitrogen, oxygen and fluorine K-edges and the sulfur LII,III edges. Electron energy loss spectra for diatomic, triatomic and polyatomic molecules have been studied. Discrete excitations have been interpreted in terms of the promotion of the respective K-shell electron to unfilled valence molecular orbitals and Rydberg orbitals. Most spectra show considerable structure above the respective K-edge, in addition to the normal K-continuum. This structure represents the simultaneous transitions of a K-shell and valence shell electrons (i.e. shake-up and shake-off events following the creation of an inner hole). In the case of molecular nitrogen and carbon monoxide, a simple core model was shown to provide an accurate description for the K-shell excited molecule. On the basis of this model, excitation and ionization energies for some exotic chemical species have been predicted from the relative energies observed in the K-shell energy loss spectra of a number of molecules. The agreement between the estimated (core analogy) and observed K-shell excitation energies for larger molecules is less satisfactory, possibly because of the large changes in molecular geometry which occur as a result of an election promotion. Finally, the carbon K-shell energy loss spectra of carbon disulfide, carbonyl sulfide and carbon tetraf1uoride show features which are possibly associated with the existence of an effective potential barrier in these molecules. / Science, Faculty of / Chemistry, Department of / Graduate

archives@tulane.edu / 1 / Xiao Li

No description available.

No description available.

Thesis (Ph. D.)--University of Technology, Sydney, 2005.

Thesis (Ph. D.)--University of Chicago, Department of Physics, 2001. / Includes bibliographical references. Also available on the Internet.

Dielectrics have been an integral part of the electron devices and will likely resume playing a significant role in the future of nanoelectronics. An important step in assessing graphene potential as an alternative channel material for future electron devices is to benchmark its transport characteristics when integrated with dielectrics. Using back-gated and dual gated graphene field-effect transistors with top high-k metal-oxide dielectric, we study the dielectric thickness dependence of the carrier mobility. We show the carrier mobility decreases after deposition of metal-oxide dielectrics by atomic layer deposition (ALD) thanks to the Coulomb scattering by charged point defects in the dielectric. We investigate a novel method for the ALD of metal-oxide dielectrics on graphene, using an ultrathin nucleation layer that enables the realization of graphene field-effect transistors with aggressively scaled gate dielectric thickness. We show the nucleation layer significantly affects the quality of the subsequently deposited dielectric. In addition, we study transport characteristics of double layer systems. We demonstrate heterostructures consisting of two rotationally aligned bilayer graphene with an ultra-thin hexagonal boron nitride dielectric in between fabricated using advanced layer-by-layer transfer as well as layer pickup techniques. We show that double bilayer graphene devices possess negative differential resistance and resonant tunneling in their interlayer current-voltage characteristics in a wide range of temperatures. We show the resonant tunneling occurs either when the charge neutrality points of the two bilayer graphene are energetically aligned or when the lower conduction sub-band of one layer is aligned with the upper conduction sub-band of the opposite layer. Finally, we study the Raman spectra and the magneto-transport characteristics of A-B stacked and rotationally misaligned bilayer graphene deposited by chemical-vapor-deposition (CVD) on Cu. We show that the quantum Hall states (QHSs) sequence of the CVD grown A-B stacked bilayer graphene is consistent with that of natural bilayer graphene, while the sequence of the QHSs in the CVD grown rotationally misaligned bilayer graphene is a superposition of monolayer graphene QHSs. From the magnetotransport measurements in rotationally misaligned CVD-grown bilayer we determine the layer densities and the interlayer capacitance. / text