Peripheral Collisions of Fast Electrons With Highly Charged Ions

Vortices are a novel feature of time-dependent atomic wave functions. A general discussion of vortices is given which relates them to nodes in the real and imaginary part of complex functions, the isolated zeros in such functions, the probability current (j) over right arrow, the velocity field (v) over right arrow, the integral of the current around isolated zeros, the density of atomic wave functions in the neighborhood of isolated zeros and the mean angular momentum averaged over the same region. The imaging theorem shows that vortices may relate to observational structures in the momentum distribution of electrons ejected from atoms by photons or by electron or positive ion impact. It is also shown that angular momentum transfer is needed in order for complex functions to exhibit isolated zeros. This unexpected connection between purely analytic properties, namely zeros, and the transfer of a physical quantity, namely angular momentum, is examined for electron impact on C5+. This connection is studied for the special case of peripheral collisions where the dipole force between incident and ejected electrons dominates.