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