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研究生:陳建道
論文名稱:自由電子自旋極化分析儀與應用
論文名稱(外文):Electron Spin Polarimeter and its Applications
指導教授:唐富欽
學位類別:碩士
校院名稱:國立成功大學
系所名稱:物理學系
學門:自然科學學門
學類:物理學類
論文種類:學術論文
畢業學年度:83
語文別:中文
論文頁數:68
中文關鍵詞:電子束
外文關鍵詞:電子自旋極化
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  以電子束為探測源或電子能譜的量測,在微觀物理實驗中是一項重要研究方法。一般是以非自旋極化電子源為工具,或量測電子的動能與動量。但若能使用自旋極化電子源為工具,或量測其自旋極化態,,則能更進一步得到完整的電子量子態(動能、動量與自旋態)資訊。電子自旋極化值與方向的變化往往與系統結構和動力現象有密切關聯,此物理量的量測能提供更精密且獨特的資訊以探討相關性質及基本物理現象,可見電子自旋極化量測在一般科學實驗上的重要性。
  自旋極化電子束和電子自旋極化量測技術,經多年的研究開發,其放能逐漸提昇。直到目前,GaAs光電子激發自旋極化電子源和micro-Mott detector可說是最優良的自旋極化電子源和電子自旋極化分析儀之一。
  我們設計發展與micro-Mott detector相類似的Mott detector, 以應用於電子自旋極化分析表面科學實驗。它具有操作電壓低(散射電壓為20kV)、散射電子能量解析度高、電子束聚焦精確穩定、體積小及結構簡單等的優點,此Mott detector已仔細校正,可量測到準確的電子自旋極化絕對值。
  本論文將討論Mott detector的理論基礎,發展過程及其種類,也詳細討論了本實驗室Mott detector的設計與操作,並量測自GaAs晶體表面光激發所產生的自旋極化電子束的自旋極化值。以探討GaAs表面負值電子親和力及光電子過程等基本物理現象。
  本論文也進一步討論我們正進行的新一代Mott detector的設計,它在更低的能量下操作,選取單一能量的電子束作自旋極化分析,此高效能的自旋極化分析儀,可應用到各種精密的電子能譜實驗中,提供更完整的資訊。


  The use of electron beams as the probing (exciting) source and/or the measurement of electron spectroscopies are important research methods. In physics, in microscope investigation, we use non spin-polarized electron source, or we measure kinetic energy and momentum of the electrons only. If we use spin-polarized electron source and/or we also measure the electron spin polarization, then we can get the complete information of electron quantum state (kinetic energy, momentum, and spin state). The change of magnitude and direction of the electron spin polarization provides the information of the investigated system structure and the kinetic phenomena, which can offer the unique and more detailed information about the properties and its basic physics phenomena.
  After many years research and development, the technique of spin-polarized electron source and the measurement of electron spin polarization have been improved gradually. So far, GaAs photoemission spin-polarized electrons source and micro-Mott detector are the most popular and powerful devices in its applications.
  We design and develop a micro-Mott electron spin polarimeter for surface science experiment. It has some advantages: low operation voltage (scattering voltage is 20 kV), high energy resolution of scattered electron, precise focus of electron beam, compact, and simple in structure. This Mott detector has been calibrated, can measure the precise electron spin polarization.
  In this thesis, we discuss the fundamental theory of Mott detector and its ceveloping history. We also compare different types of spin polarimeter and its calibration method. We apply our designed micro-Mott detector to measure the photoemission electrons from-a negative electron affinity GaAs surface (covered with Cs and O2 films) irradiated with infrared laser beams. This measurement provides important information of negative electron affinity phenomena, surface structure and photoemission process.
  In this thesis, we alao discuss the design of a new generation of Mott detector, it operates at much lower voltage and select particular energy range of electron beams in its spin polarization analysis. This high efficiency spin polarimeter can provide informations about energy, momentum, and spin state of electrons at one time, be suitable in many such precise electron spectroscpoy experiments.

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