Title page for etd-0714108-111912


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URN etd-0714108-111912
Author Cheng-Lien Chan
Author's Email Address ipoton@gmail.com
Statistics This thesis had been viewed 5331 times. Download 3102 times.
Department Physics
Year 2007
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Magnetic Studies on the Radicals of Methyl Viologen
Date of Defense 2008-06-07
Page Count 81
Keyword
  • room temperature
  • ferromagnetism
  • Methyl Viologen
  • ferromagnet
  • EPR
  • radical
  • SQUID
  • magnetic
  • g-factor
  • Abstract Abstract
      Methyl Viologen is a kind of organic molecular magnet of current interest which comprises with organic radicals (unpaired electrons). The molecular formula of the sample is (C12H14N2)2+X2-, where “X2-” denotes a non-magnetic anion (CdI42-, I3-I- etc.). We perform the magnetization (using SQUID magnetometer) and electron paramagnetic resonance (EPR) measurements. Two absorption peaks are observed in EPR spectrum indicating that there are two radical forms in our samples. One of the radicals exists in every sample having the g1-factor value 2.004. The other radical which has the g2-factor 2.001 exists only in certain samples. Interestingly, we find that these samples exhibit ferromagnetism at room temperature. We use Lorentzian profile to quantitatively analyze the EPR spectrum of the samples and derive the ratio (A2/A1) of two different absorption peaks, which represents the amount of g2 radical. The remanent magnetization and saturation magnetization are found to increase as the ratio value increases, indicating that the strength of ferromagnetism is strongly correlated with g2 radical.
    Advisory Committee
  • Jiunn-Yuan Lin - chair
  • Hsiung Chou - co-chair
  • Kuan-Jiuh Lin - co-chair
  • Hung-Duen Yang - advisor
  • Files
  • etd-0714108-111912.pdf
  • indicate access worldwide
    Date of Submission 2008-07-14

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