Generation of vortex electrons by atomic photoionization

Abstract

We explore the process of orbital angular momentum (OAM) transfer from a twisted light beam to an electron in atomic ionization within the first Born approximation. The characteristics of the ejected electron are studied regardless of the detection scheme. We find that the outgoing electron possesses a definite projection of OAM when a single atom is located on the propagation axis of the photon, whereas the size of the electron wave packet is solely determined by the energy of the photon rather than by its transverse coherence length. Shifting the position of the atom yields a finite dispersion of the electron OAM. We also study a more experimentally feasible scenario -- a localized finite-sized atomic target -- and develop representative approaches to describing coherent and incoherent regimes of photoionization.