We present measurements and calculations of the momentum distribution of electrons emitted during the ion-atom collision $10\mathrm{keV}/\mathrm{u}$ ${\mathrm{He}}^{2+}+\mathrm{He}\to {\mathrm{He}}^{+}+{\mathrm{He}}^{2+}+e^{-}$, 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.

• Received 10 September 2013

DOI:https://doi.org/10.1103/PhysRevLett.112.083201