||Artist's conception of JILA's new technique for measuring the electron's roundness, or electric dipole moment (EDM). The method involves trapping molecular ions of hafnium fluoride (red and blue spheres, respectively) in spinning electric and magnetic fields. Researchers measure changes over time in the ?spin? direction of the molecules' unpaired electrons (arrows in yellow spheres), which act like tiny bar magnets. Specific patterns in the rate of change, reflecting alterations in the gap between two magnetic energy levels in the molecules, would indicate the existence and size of an EDM.
See also http://www.nist.gov/pml/div689/20131205_edm.cfm.