Low temperature charge transfer.
Item
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Title
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Low temperature charge transfer.
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Identifier
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AAI9417515
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identifier
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9417515
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Creator
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Xia, Bo.
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Contributor
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Adviser: Myron Strongin
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Date
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1994
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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 | Chemistry, Physical
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Abstract
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Alkali metal-ammonia films were chosen as a vehicle to study the phenomena of low temperature charge transfer. Photoelectron spectroscopy and resistivity measurements were used to detect small changes within these films. The results of the resistivity measurement show that some chemical reactions happened in the alkali metal-ammonia films at temperatures as low as 7 K. As the sample temperature increased to above 25 K, drastic changes were observed in both photoelectron spectroscopy and resistivity measurement. In the resistivity measurement, the film resistance decreased and the change was irreversible, which is contrary to the results of the controlled experiment using alkali metal-inert gas films. The resistance change with temperature in these control films is a purely physical process and gives us basis for understanding the chemical process in the alkali metal-ammonia films. In the photoemission spectra for the alkali metal-ammonia films, peaks which have molecular nitrogen characteristics were observed. A modified Mott's low temperature oxidation model was used to interpret the experimental results. Electrons tunneling into the ammonia media and dissolving into it are the cause for the low temperature chemical reactions in the alkali metal-ammonia film. Experimental results demonstrated that a small amount of ammonia-covered alkali metal films did not show any chemical changes with temperature and significant amount of ammonia was needed in order to observe the irreversible changes in alkali metal-ammonia films.;The last chapter of the thesis is a photoemission study of ytterbium-C{dollar}\sb{lcub}60{rcub}{dollar} bilayers at room temperature. The experimental results are compared to those reported for alkali metal fullerides and ytterbium isolated in xenon or solid ammonia.
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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.
