Test of the ionization threshold law through spin-dependent collisions of electrons and hydrogen atoms.
Item
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Title
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Test of the ionization threshold law through spin-dependent collisions of electrons and hydrogen atoms.
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Identifier
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AAI9207076
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identifier
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9207076
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Creator
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Guo, Xiao-Qin.
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Contributor
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Adviser: Michael S. Lubell
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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, Atomic
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Abstract
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Using a crossed-beam apparatus with polarized electrons and polarized atoms, the ionization spin asymmetry for atomic hydrogen, defined as{dollar}{dollar}A = {lcub}\sigma(\uparrow\downarrow) - \sigma( \downarrow\downarrow) \over \sigma(\uparrow\downarrow) + \sigma( \downarrow \downarrow){rcub},{dollar}{dollar}has been measured for incident electron energies between 13.67 to 15.27 eV. In the energy range within 0.5 eV above threshold, our results reveal the failure of the conventional Wannier theory which predicts a constant spin-asymmetry. For the full energy range investigated, the presence of structure is clearly evident and is quantitatively inconsistent with any existing theoretical calculation. Moreover, our reinvestigation of the results of four previous experimental studies, all of which claimed to support the Wannier theory, show deficiencies. Our conclusion in this regard is based upon extensive statistical analyses of the published data. Finally, our reexamination of the Wannier theory also indicates a lack of selfconsistency in the theory itself.
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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.
