Parity Violation of Electroweak Force in Phase Transitions of Single Crystals of D- and L-Alanine and Valine

Abstract

Three kinds of experiments have been designed in attempting to observe theparity violation of electroweak force at the phase transition of singlecrystals of D- and L-alanine and valine.(1) An obvious λ phasetransition at 270 ± 1 K was shown in the specific heat measurement ofalanine and valine enantiomers by differential scanning calorimetry. Thebiologically dominant L-enantiomer was found to have lower energy. (2)Magnetization of single crystals of D- and L-alanine and D-valine weremeasured as a function of temperature using the SQUID magnetometer. Thedifference of the mass susceptibility χ_ρ ∼ T curve between theD-alanine and L-alanine is attributable to the variation of intramoleculargeometry of chirality density, which is related to the parity violationenergy shift of a chiral molecule and is a consequence of the short rangeof the weak interaction between the nuclei and electrons. (3) Laser Ramanspectra of D- and L-alanine at different low temperatures (100 K, 250 K,260 K, 270 K, 280 K and 290 K) showed that the second order Cα–Hdeformation modes at 2606 cm^-1, 2724 cm^-1 of D-alanine vanishedat 270 K but reappeared at 100 K. In the same method, L-alanine has nosuch phenomenon. An obvious decrease in the scattering intensity of themethyne group C^α–H stretching mode at 2964 cm^-1 in D-alanineoccurs at the λ transition temperature. We present our experimentsinvolving the possible relevance of Z⁰ force with Salam's putativephase transition in the origin of homochirality.