Generation of propagating electron vortex states in photodetachment of H−

Abstract

Generation of propagating electron vortex states in ionization of ${\mathrm{H}}^{\ensuremath{-}}$ by short, circularly polarized laser pulses is studied within the strong-field approximation. The latter, being particularly suitable for treating negative ions, is shown to be gauge independent for an $s$-electron system like ${\mathrm{H}}^{\ensuremath{-}}$. Most importantly, it is demonstrated that the orbital angular momentum from the laser field can be efficiently transferred to photoelectrons, thus resulting in high orbital angular momenta electron vortex states. The conditions for this to happen are formulated and visualized with the help of coarse-grained probability distributions of photoelectrons, which are calculated by Monte Carlo method.