Effect of beta radiation on the crystallization of sodium chlorate from water: a new type of asymmetric synthesis.
Sodium chlorate is an achiral molecule that crystallizes from water in the chiral space group P2(1)3. In the absence of chiral perturbations, a random distribution of (+) and (-) crystals is obtained. Kondepudi(2) has shown that constantly stirring an evaporating NaClO(3) solution gives mostly either (+) or (-) crystals. Repeating this experiment many times gives equal numbers of (+) and (-) sets of crystals. Herein we report that when evaporating aqueous NaClO(3) is subjected to beta particles from an Sr-90 source, an asymmetric distribution of (+) and (-) crystals favoring the (+) crystals is obtained. The beta particles are energetic polarized electrons that are approximately 80% of left-handed helicity. By a poorly understood mechanism, the spin polarized electrons produce chiral nucleating sites that favor formation of the (+)-NaClO(3) crystals. Exposure of the evaporating solution instead to energetic positrons from an Na-22 source yields mainly (-)-NaClO(3) crystals. Polarized positrons are of predominantly right-handed helicity. One may conclude that the chirality of the radiation is correlated with the chirality of the crystals being generated.
Mahurin
S
S
Department of Physics, University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
McGinnis
M
M
Bogard
J S
JS
Hulett
L D
LD
Pagni
R M
RM
Compton
R N
RN