Nonresonant photon dressing in spin one quadrupolar systems.
Item
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Title
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Nonresonant photon dressing in spin one quadrupolar systems.
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Identifier
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AAI9304752
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identifier
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9304752
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Creator
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Zhuang, Yi-Li.
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Contributor
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Adviser: Robert A. Marino
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Date
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1992
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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, Nuclear
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Abstract
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The main part of this thesis is a study of the effects of nonresonant photon dressing on spin 1 pure quadrupolar system with symmetric EFG. Energy levels of spin 1 nuclei dressed by linearly or circularly polarized photons were theoretically derived and numerically analyzed. In both cases, the degeneracy of m{dollar}\sb\zeta{dollar} equals {dollar}\pm{dollar}1 states is not lifted, so only one line can be excited and it is shifted up in frequency. The energy levels are found to depend on the angle {dollar}\theta{dollar} between the principle EFG {dollar}\zeta{dollar} axis and the dressing field. Since most NQR samples are polycrystalline, a general formula for powder patterns due to photon dressing was derived and numerical examples were plotted for the case of linearly polarized photons, spin 1 and {dollar}{lcub}3\over2{rcub},{dollar} and circularly polarized photons, spin 1. In all of these cases, NQR lines are broadened, and have a peak located at {dollar}\theta{dollar} = 90{dollar}\sp\circ{dollar}.;Energy levels of photon dressed protons in zero static field are analyzed for the purpose of discussing {dollar}\sp{14}N{dollar} spin-echo time. Protons are shown to reorient between {dollar}\pm{lcub}1\over2{rcub}{dollar} states rapidly, so that their local field tends to average out.;Powdered crystalline samples Trimethylamine (TMA), Triethylenediamine (TED), and Hexanethylenetetramine (HMT) all with symmetric EFG were experimentally investigated by {dollar}\sp{14}N{dollar} NQR. For circularly polarized dressing of 25 G peak, no NQR frequency shift was observed; a monotonic line narrowing was observed in TMA and TED, but not HMT; fine structure details of TED and HMT were revealed as a result of the line narrowing, but the cause of the fine structure was not determined. Experimental results are in good agreement with theory.;A minor portion of this thesis is to study the effects of annealing and hydrogenation on short-range order in amorphous III-V compounds through NMR linewidth. {dollar}\alpha{dollar} - GaP, {dollar}\alpha{dollar} - GaAs, and {dollar}\alpha{dollar} - GaAs: H grown on single crystal alkali halide substrates by rf-sputtering have been studied. The results were compared with that of previous measurements on {dollar}\alpha{dollar} - GaP and {dollar}\alpha{dollar} - GaAs grown on different substrates at different temperature. The study showed that sample microstructure is directly influenced by sample preparation conditions, however, the presence of 10% hydrogen in the sample did not influence the NMR linewidth at room temperature nor 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.
