Positron transport in solids and the interaction of positrons with surfaces.
Item
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Title
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Positron transport in solids and the interaction of positrons with surfaces.
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Identifier
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AAI9207088
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identifier
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9207088
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Creator
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Kong, Yuan.
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Contributor
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Supervisor: Kelvin G. Lynn
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Date
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1991
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Condensed Matter | Physics, Radiation | Physics, Nuclear
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Abstract
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In studying positron transport in solids, a two-stream model is proposed to account for the epithermal positrons. Thus positron implantation, thermalization, and diffusion processes are completely modeled. Experimentally, positron mobility in thermally grown SiO{dollar}\sb2{dollar} is measured in a sandwiched structure by using the Doppler broadening technique. Positron drift motion and the electric field configuration in a Si surface buried under overlayers are measured with the positron annihilation {dollar}\gamma{dollar}-ray centroid shift technique. These studies are not only important in measuring positron transport and other properties in complicated systems, they are also of practical significance for material characterizations.;In studying positron interactions with surfaces, a multiple-encounter picture is proposed of thermal positron participating in the surface escape processes. Positron trapping into the surface image potential is also studied considering the long range nature of the image potential. Experimentally, the positron annihilation induced Auger electron spectroscopy (PAES) is used to study an ionic insulator surface KCl(100). Temperature dependent as well as positron energy dependent measurements are carried out. The experimental evidence suggests that the Auger electrons are possibly associated with positrons bound to Cl ions in the near surface region. The surface sensitivity and the non-destructiveness of the PAES technique are also examined for measuring the KCl(100) surface sputtering damage and the annealing behavior.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
