Open AccessAbove-threshold ionization driven by Gaussian laser beams: beyond the electric dipole approximation
Author(s) -
Birger Böning,
S. Fritzsche
Publication year - 2021
Publication title -
journal of physics. b, atomic molecular and optical physics/journal of physics. b, atomic, molecular and optical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.725
H-Index - 121
eISSN - 1361-6455
pISSN - 0953-4075
DOI - 10.1088/1361-6455/ac0fef
Subject(s) - physics , ionization , atomic physics , dipole , discrete dipole approximation , laser , gaussian , photoelectric effect , gaussian beam , beam (structure) , offset (computer science) , momentum (technical analysis) , electron , computational physics , optics , quantum mechanics , ion , finance , computer science , economics , programming language
Strong-field atomic experiments have recently become sensitive to nondipole (magnetic) interactions. In particular, photoelectrons emitted in above-threshold ionization possess a nonzero momentum along the beam axis as a result of the Lorentz force. Here, we show how this longitudinal momentum can be theoretically calculated based on a nondipole strong-field approximation that accounts not only for the temporal but also the spatial dependence of the laser field in the photoelectron continuum. If the driving laser beam is approximated as a plane wave, the theoretical values differ from known experimental results by a constant offset. We demonstrate that this offset can successfully be removed if a realistic Gaussian beam profile is accounted for in the quantum description of ATI. We also discuss the influence of the size of the beam waist in the focus.