物理化学学报 >> 2008, Vol. 24 >> Issue (05): 743-748.doi: 10.1016/S1872-1508(08)60031-5

研究论文 上一篇    下一篇

D-和L-丙氨酸的磁手性相变

王文清; 沈新春; 龚   

  1. 北京大学化学与分子工程学院应用化学系, 北京分子科学国家实验室, 北京 100871; 清华大学医学院, 北京 100084
  • 收稿日期:2007-10-29 修回日期:2008-01-28 发布日期:2008-05-05
  • 通讯作者: 王文清 E-mail:wangwqchem@pku.edu.cn

Magnetic Chirality Transitions of D- and L-Alanine

WANG Wen-Qing; SHEN Xin-Chun; GONG Yan   

  1. Beijing National Laboratory for Molecular Sciences, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China; Medical College of Tsinghua University, Beijing 100084, P. R. China
  • Received:2007-10-29 Revised:2008-01-28 Published:2008-05-05
  • Contact: WANG Wen-Qing E-mail:wangwqchem@pku.edu.cn

摘要: 利用变温直流磁化率测定, 在外加磁场强度为1 T, 磁场平行晶体c轴, 发现在温度270 K, D-和L-丙氨酸发生磁手性相变. 结合中子衍射确定磁手性相变机制为, D-和L-丙氨酸中的(N+H)有类金属氢原子特性, 在相变点270 K, 由(N+H)释放的电子自旋有磁手性. 用变温偏振拉曼光谱进一步证明, D-丙氨酸中的(N+H)的电子自旋(↑), 而L-丙氨酸中的电子自旋(↓), 处于高低不同的能态.磁手性相变(宇称和时间反演都破缺)能差为10-4-10-5 eV·molecule-1.

关键词: 磁手性相变, D-和L-丙氨酸, 直流磁化率, 变温偏振拉曼光谱

Abstract: Achiral spin state of (N+H) in D- and L-alanine was established by monitoring the temperature dependence of dc-magnetic susceptibility (dc: direct current) under the external magnetic field of 1 T. An intrinsic spin chirality of electrons in the atomic magnetic dipole moment of (N+H) was also supported by polarized Raman spectroscopy. Magnetic chirality was associated with a strongly correlated electron system that was related to spin rigidity. Raman vibrational spectra were unrelated to structural chirality but could reflect spin chirality due to the reversal of motion breaking. The spin transition of (N+H) occured at 270 K without bond breaking but was assisted by an intermediate hydrogen bond elongation, splitting and reformation with NH+3 torsion. The energy difference of spin chirality transitions between D- and L-alanine was around 10-4-10-5 eV·molecule-1.

Key words: Magnetic chirality transition, D- and L-alanine, Direct current magnetic susceptibility, Polarized Raman spectroscopy

MSC2000: 

  • O641