Above-threshold ionization driven by Gaussian laser beams: beyond the electric dipole approximation. (11th August 2021)

• Record Type: Journal Article
• Authors: Böning, B; Fritzsche, S
• Is Part Of: Journal of physics. Volume 54:Number 14(2021)
• Publication Date: 2021-08-11
• Subjects: above-threshold ionization -- non-dipole effects -- strong-field approximation -- Gaussian laser beams; Atoms -- Periodicals; Molecules -- Periodicals; Optics -- Periodicals; Nuclear physics -- Periodicals; 539.6
• DOI: 10.1088/1361-6455/ac0fef
• Languages: English
• ISSNs: 0953-4075

Abstract

Abstract: 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.