Angular momentum distribution of electrons in above-threshold ionization

We examine a quantum optical model describing absorption of photons above an ionization threshold in multiphoton ionization. We calculate 12-photon ionization of the hydrogen atom by a strong, linearly polarized laser pulse. The angular momentum distribution of photoelectrons in the consecutive peaks depends on the intensity of the laser but reveals the presence of only a few of the lowest angular momenta. No ‘‘peak switching’’ is observed, but a finite-number-of-continua model becomes unstable at an intensity of ∼${10}^{\mathrm{-}3}$ a.u. (∼${10}^{14}$ W/${\mathrm{cm}}^2$).