Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (10): 2597-2603.doi: 10.3866/PKU.WHXB20100912

• THERMODYNAMICS,THERMOCHEMISTRY AND SOLUTION CHEMISTRY • Previous Articles     Next Articles

Cryogenic Magnetic Transition of D- and L-Alanine: Magnetic Field Dependence of Specific Heat and DC Magnetic Susceptibility

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

  1. 1. Beijing National Laboratory for Molecular Sciences, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China;
    2. School of Materials Science&Engineering, Beijing Institute of Fashion Technology, Beijing 100029, P. R. China
  • Received:2010-03-19 Revised:2010-05-21 Published:2010-09-27
  • Contact: WANG Wen-Qing E-mail:wangwqchem@pku.edu.cn
  • Supported by:

    The project was supported by the National Key Basic Research Programof China (973) (2004-973-36) and National Natural Science Foundation of China (20452002).

Abstract:

To understand the intrinsic asymmetries of D- and L-alanine crystal lattices, the magnetic field dependence of zero-field and 1, 3, and 5 T on the heat capacity were measured from 2 to 20 K. The obtained heat capacity data shows linear behavior that follows: C(T)=aT3+b/T2. The first aT3 term is from the lattice phonon contribution with CV=(12/5)π4R(T/θD)3 (θD is the Debye temperature). The second b/T 2 term in the fitting formula is the magnetic contribution. In this experiment, the obtained Cp data for the D- and L-alanine single crystals show a Boson peak, which is seen as a maximum in the Cp /T 3 versus T plots in the low temperature region from 2-20 K at different fields. The four Cp /T 3 versus T curves show a split between D-andL-alanine from 2-12 K and this is due to the magnetic contribution. This is absent between 12 and 20 K, which indicates the Schottky anomaly. The temperature of the Boson peak is 9.44 K for D-alanine and 10.86 K for L-alanine, and θD is 151.5 and 152.7 K for D-alanine and L-alanine in zero-field, respectively. DC magnetic susceptibility data show the chiral behavior in nuclear spin-electron spin hyperfine interaction at very low temperature.

 

Key words: Magnetic transition, D- and L-alanine, Heat capacity, DC magnetic susceptibility, Boson peak, Debye temperature

MSC2000: 

  • O642