Acta Phys. -Chim. Sin. ›› 2005, Vol. 21 ›› Issue (10): 1186-1194.doi: 10.3866/PKU.WHXB20051026

• Review • Previous Articles    

Temperature- induced Phase Transitions in Chiral Amino Acids——Search of Spontaneous Parity- Breaking and Restoration

WANG Wen-qing; MIN Wei; GONG Yan   

  1. Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871
  • Received:2005-03-14 Revised:2005-04-26 Published:2005-10-15
  • Contact: WANG Wen-qing

Abstract: The effects of temperature on the parity-violating entropy and energy differences of chiral molecules are investigated both theoretically and experimentally. Statistical thermodynamics calculations indicate the possible occur-rence of sign reversal of parity-violating entropy difference at different temperatures, which is supported by temperature-dependent polarized Raman spectra of D-alanine and L-alanine. An incoherent spontaneous symmetry breaking is proposed to describe the bifurcation mechanism between mirror-image systems at the critical temperature, in which usually violated parity symmetry will be dynamically restored again. An asymmetric double-well potential with a tiny parity-violating energy difference (PVED) in the depths of the two potential wells showed that the presence of PVED can lead to the enrichment of L-form amino acid. Tunneling dynamics of amino acids with PVED provides a plausible mechanism for much faster development of homochirality.

Key words: Temperature effect, Temperature-conformation-PVED relation, Parity-violating entropy difference, Tunneling dynamics, Alanine enantiomers