Strong-field ionization provides unique means to address complex dynamics of an electron in competing Coulomb and laser fields. A recent streak camera experiment [M. Kübel et al., Phys. Rev. Lett. 119, 183201 (2017).] analyzed asymmetries in the low-energy region of ejected electron momentum distributions and associated them with multiple rescattering of the electron on the parent ion. In this work we directly confirm the multiple-rescattering nature of the asymmetry in the low-energy region. Such electron-ion collisions cannot be described within one-dimensional simulations even taking into account focal-volume averaging. Using a time-dependent Schrödinger equation simulation in two dimensions supplemented by insights from the strong-field semiclassical approximation we identify the dominant interference features of the complex photoelectron momentum distributions and find their traces in the experiment. In particular, the holographic structures remain visible in experimental results averaged over the carrier-envelope phase (CEP). In the case of individual momentum distributions when the CEP or delay between the two pulses is varied, the structures arising due to rescattering events are influenced by interfering electrons ionized at the main peaks of the electric field. With an increase of experimental resolution, such structures record the electron dynamics on a sub-laser-cycle timescale.

• Received 12 July 2019

DOI:https://doi.org/10.1103/PhysRevA.100.063410