Vortices Associated with the Wave Function of a Single Electron Emitted in Slow Ion-Atom Collisions

We present measurements and calculations of the momentum distribution of electrons emitted during the ion-atom collision 10 kev /u He super(2+) + He arrow right He super(+) + He super(2+) + e super(-), which show rich structures for ion scattering angles above 2 mrad arising dominantly from two-electron states. Our calculations reveal that minima in the measured distributions are zeros in the electronic probability density resulting from vortices in the electronic current.