論文摘要
Methyl Viologen是一種帶有自由基(radical)的有機分子磁鐵，其分子式為(C12H14N2)2+X2-，其中X2-代表不具磁性的陰離子(CdI42-、I3-I-等)，我們對它進行了磁性量測(SQUID magnetometer)、電子順磁共振(EPR)等實驗。在EPR的量測中，我們觀察到兩個吸收峰，對應到兩種自由基的存在。其中之ㄧ的g1-factor的值為2.004，可以在每一個樣品中觀察到。另一個g2-factor的值為2.001，卻只存在於某些特定的樣品，有趣的是，這些樣品在室溫就具有鐵磁性，表示鐵磁性的行為與g2自由基有關。進一步用Lorentzian profile 去量化分析EPR spectrum的數據，以兩個吸收峰的面積比例A2/A1表示g2自由基的多寡。結果發現此值越大，殘留磁性與飽和磁化強度皆變大。也就表示g2自由基越多，鐵磁性就越強。

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.

目錄
Abstract 1
論文摘要 2
目錄 3
圖目錄 5
表目錄 9
第一章 簡介(Introduction) 10
1-1 前言 10
1-2 具有自由基(radical)的有機分子之磁性介紹 12
1-3 研究動機與過程 17
第二章 儀器與理論介紹 19
2-1 超導量子干涉磁量儀(SQUID magnetometer) 19
2-2 電子順磁共振(EPR) 34
2-3 磁性的種類 36
2-4 磁的偶合機制 43
第三章 實驗方法 47
3-1 樣品製作方法 47
3-2 Methyl Viologen樣品介紹 50
3-3 磁性量測 54
3-4 EPR量測 55
3-5 紫外光誘發自由基的磁性研究 55
第四章 實驗結果與分析 56
4-1 MV-CdI4的磁性實驗結果 56
4-2 MV-I3I的磁性實驗結果 64
4-3紫外光誘發自由基的磁性研究結果 65
第五章 結論 68
附錄 69
參考文獻 76

參考資料
[1] C. J. Ho, J. L. Her, C. P. Sun, C. C. Yang, C. L. Huang, C. C. Chou, Lu-Lin Li, K. J. Lin, W. H. Li, J. W. Lynn, and H. D. Yang, Phys. Rev. B 76, 224417 (2007).
[2] A. Rajca, J. Wongsriratanakul, and S. Rajca, Science 294, 1503 (2001).
[3] W. A. Pryor, “Introduction to Free Radical Chemistry”, (1966).
[4] M. Tamura, Y. Nakazawa, D. Shiomi, K. Nozawa, Y. Hosokoshi, M. Ishikawa, M. Takahashi and M. Kinoshita, Chem. Phys. Lett. 186, 401 (1991).
[5] Y. Nakazawa, M. Tamura, N. Shirakawa, D. Shiomi, M. Takahashi, M. Kinoshita, and M. Ishikawa, Phys. Rev. B 46, 8906 (1992).
[6] M. Takahashi, P. Turek, Y. Nakazawa, M. Tamura, K. Nozawa, D. Shiomi, M. Ishikawa, and M. Kinoshita, Phys. Rev. Lett. 67, 746 (1991).
[7] P.-M. Allemand, K. C. Khemani, A. Koch, F. Wudl, K. Holczer, S. Donovan, G. Gruner, and J. D. Thompson, Science 253, 301 (1991).
[8] K. Mukai, K. Konishi, K. Nedachi, and K. Takeda, J. Phys. Chem. 100, 9658 (1996).
[9] K. Takeda, T. Hamano, T. Kawae, M. Hidaka, M. Takahashi, S. Kawasaki, and K. Mukai, J. Phys. Soc. Jpn. 64, 2343 (1995).
[10] M. Mito, K. Takeda, K. Mukai, N. Azuma, M. R. Gleiter, C. Krieger, and F. A. Neugebauer, J. Phys. Chem. B 101, 9517 (1997).
[11] K. Mukai, S. Kawasaki, J. B. Jamali, and N. Achiwa, Chem. Phys. Lett. 241, 618 (1995).
[12] M. Mito, H. Nakano, T. Kawae, M. Hitaka, S. Takagi, H. Deguchi, K. Suzuki, K. Mukai, and K. Takeda, J. Phys. Soc. Jpn. 66, 2147 (1997).
[13] S. Tomiyoshi, T. Yano, N. Azuma, M. Shoga, K. Yamada, and J. Yamauchi, Phys. Rev. B 49, 16031 (1994).
[14] K. Mukai, M. Nuwa, T. Morishita, T. Muramatsu, T. C. Kobayashi, and K. Amaya, Chem. Phys. Lett. 272, 501 (1997).
[15] A. Rajca, Chem. Eur. J. 8, 4834 (2002).
[16] S. J. Blundell and F. L. Pratt, J. Phys.: Condens. Matter 16, 771 (2004).
[17] M. Kinoshita, Jpn. J. Appl. Phys. 33, 5718 (1994).
[18] L. Krusin-Elbaum, D. M. Newns, H. Zeng, V. Derycke, J. Z. Sun and R. Sandstrom, Nature 431, 672 (2004).
[19] 楊鴻昌, 物理雙月刊 24, 652 (2002).
[20] 黃儀芬,“含自由基的奈米級釩金屬氧化物之磁性研究”,國立中山大學物理研究所碩士論文, (2006).
[21] S. Chikazumi 著,張煦、李學養合譯,“磁性物理學”, (1981).
[22] 魏炯權, “電子陶瓷材料”, (2004)
[23] J. H. Russell and S. C. Wallwork, Acta Cryst. B28, 1527 (1972).