title: Low-energy structures in strong field ionization revealed by quantum orbits.
abstract: Experiments on atoms in intense laser pulses and the corresponding exact ab initio solutions of the time-dependent Schrödinger equation (TDSE) yield photoelectron spectra with low-energy features that are not reproduced by the otherwise successful work horse of strong field laser physics: the "strong field approximation" (SFA). In the semiclassical limit, the SFA possesses an appealing interpretation in terms of interfering quantum trajectories. It is shown that a conceptually simple extension towards the inclusion of Coulomb effects yields very good agreement with exact TDSE results. Moreover, the Coulomb quantum orbits allow for a physically intuitive interpretation and detailed analysis of all low-energy features in the semiclassical regime, in particular, the recently discovered "low-energy structure" [C. I. Blaga, Nature Phys. 5, 335 (2009) and W. Quan, Phys. Rev. Lett. 103, 093001 (2009).
authors.affiliation: Institut für Physik, Universität Rostock, 18051 Rostock, Germany.
authors.forename: Tian-Min
authors.initials: TM
authors.lastname: Yan
authors.forename: S V
authors.initials: SV
authors.lastname: Popruzhenko
authors.forename: M J J
authors.initials: MJ
authors.lastname: Vrakking
authors.forename: D
authors.initials: D
authors.lastname: Bauer