The direction of an electron's spin is sufficient to determine the decomposition rate of the two mirror-image forms of a molecule.
Richard Rosenberg of Argonne National Laboratory in Illinois and his colleagues drew this conclusion after firing X-rays at a magnetic iron–nickel alloy coated with thin layers of 2-butanol. This freed electrons from the alloy, and their spins aligned with its magnetic field.
With the alloy magnetized in one direction, the electrons tended to increase the rate that right-handed 2-butanol fell apart in response to light by about 10%; the opposite field caused a similar effect in left-handed molecules. The two forms of the molecule are shown above.