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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

Analysis of quantum semiconductor heterostructures by ballistic electron emission spectroscopy

Guthrie, Daniel K. 12 1900 (has links)
No description available.
32

Investigation of the lifetime spectrum of monoenergetic positrons in silicon involving secondary electrons emission from a carbon foil as start signal, and positron annihilation spectroscopy studies of strontium titante

Zhang, Yu, 張毓 January 2013 (has links)
A proposed design of the variable energy positron annihilation spectroscopy (VEPALS) system based on secondary electron (SE) emission from a thin carbon foil has been investigated practically. The SE yield and the positron transmission coefficient were investigated as a function of the positron beam energy, the annular electrode potentials, and the column lengths of the annular electrode. The positron lifetime spectra of single crystal p-type silicon(Si) sample under different annular electrode potentials were analyzed. The result gives a supposed annular electrode potential of 1.5 kV. In view of this, the positron lifetime spectra were measured under different positron beam energy by fixing the annular electrode potential. It can be seen that all the spectra have the main p-type Si bulk lifetime component of 234 ps occupying more than 60% intensities. The intensity of the 234 ps component reaches up to 84.5 ±1.3 % when the positron beam energy is 15 keV. Further, the origin of the satellite peaks in the positron lifetime spectra are also investigated. It has been shown that the satellite peaks is attributed to the overflowing positrons on the MCP detector. The single crystal strontium titanate (STO) substrates after vacuum annealing treatment have been investigated in detail by several experimental techniques. The crystallization changes induced by the vacuum annealing were investigated by X-ray diffraction(XRD). Secondary phases were occurred after annealing treatment. The measured X-ray photoelectron spectroscopy (XPS) at O1s and C1s core levels were analyzed. The additional peaks after annealing are attributed to hydroxyl species, C-OH compounds, and carbonates. The variable energy Doppler broadening spectroscopy (VEDBS) and the traditional coincidence positron annihilation lifetime spectroscopy (PALS) were used to probe defects in STO samples. For long annealing time samples, the S parameters decrease below the reference level. The S-Wplot suggests that almost the same type of vacancy defects were induced during the annealing treatment. The positron lifetime results suggest that the main defects in annealed samples are oxygen monovacancies or divacancies and Sr-O vacancy complexes. The sample with annealing time of 110h has minimum positron effective diffusion length and maximum average lifetime, which is attributed to the increase of the vacancy-type defects during the long annealing treatment. / published_or_final_version / Physics / Master / Master of Philosophy
33

Electronic spectroscopy of cobalt monohalides and nitric oxide

Wong, Lai, Ally, 王麗 January 2003 (has links)
published_or_final_version / abstract / toc / Chemistry / Master / Master of Philosophy
34

Some positron annihilation studies on highly doped and supersaturated N-type silicon

Ho, King-fung., 何競豐. January 2004 (has links)
published_or_final_version / abstract / toc / Physics / Doctoral / Doctor of Philosophy
35

Electronic spectroscopy as a probe of heterogeneity in the local environment of polar aromatic chromophores in proteins and free solution.

Purkey, Robert Michael. January 1972 (has links)
No description available.
36

All-electron and full-potential positron annihilation calculations for intrinsic and defective zinc and zinc oxide

Zhou, Taojun. January 2007 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.
37

High resolution microanalysis of alloy steel

Vatter, Ian A. January 1993 (has links)
No description available.
38

Relativistic atomic structure calculations applied to electronic transitions in atoms

Sankari, A. (Anna) 29 February 2008 (has links)
Abstract In this thesis, the electronic structure of selected atoms was investigated by means of electron and uorescence spectroscopy. Synchrotron radiation was used to excitate atoms in gas phase. In particular, the photoionization and subsequent Auger decay processes in metal vapours were studied as well as the resonant Auger decay in rare gases. The experimental results were analyzed together with theoretical predictions obtained utilizing the multiconfiguration Dirac-Fock method.
39

FTIR and XPS of congruent and stoichiometric LiNbO3

Hung, Wing Wa 01 January 2003 (has links)
No description available.
40

Electronic spectroscopy as a probe of heterogeneity in the local environment of polar aromatic chromophores in proteins and free solution.

Purkey, Robert Michael. January 1972 (has links)
No description available.

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