Angular Distributions for Double Ionization of ${\mathrm{Li}}^{-}$ by an Ultrashort, Intense Laser Pulse

We predict photoelectron angular distributions for double ionization of ${\mathrm{Li}}^{-}$ by both weak and intense ultrashort, linearly polarized laser pulses by direct numerical integration of the three-dimensional, time-dependent Schrödinger equation. ${\mathrm{Li}}^{-}$ is treated as a two-active electron system. Near threshold, for low intensity we recover general features of angular distributions for one-photon double ionization. For the intense field (multiphoton) case, the photoelectron angular distribution changes significantly, particularly in directions parallel and perpendicular to the laser polarization axis.