Recoil-ion-momentum spectrum for few-photon double ionization of helium

Abstract

We provide an efficient and accurate numerical method to deduce the recoil-ion-momentum spectrum of He from the two-electron momentum distribution, which is obtained by solving the full-dimensional time-dependent Schr\"odinger equation. We apply this method to study the ion spectra of one-photon double ionization and two-photon sequential and nonsequential double ionization of He. The present calculations agree rather well with the absolute magnitude of the recoil-ion triply differential cross sections published recently [S. A. Abdel-Naby, M. S. Pindzola, and J. Colgan, Phys. Rev. A 86, 013424 (2012); S. A. Abdel-Naby et al., Phys. Rev. A 87, 063425 (2013)]. Nevertheless, significant differences are also found in several detailed features of the spectra and straightforward physical analysis indicates that the present results appear more reasonable, which should be confirmed by future experiments or additional independent calculations.