Above-Threshold Ionization: From Classical Features to Quantum Effects

Low-energy peak structure in strong-field ionization by midinfrared laser pulses: Two-dimensional focusing by the atomic potential

“…One of the important fundamental processes of strong-field laser-matter interaction is above-threshold ionization (ATI), a process generally considered to be well understood [6][7][8].…”

Cutoffs of high-energy plateaux for atomic processes in an intense elliptically polarized laser field

“…These features are well known in multiphoton processes involving bound atomic states (such as high-harmonic generation (HHG) and above-threshold ionization/detachment (ATI/ATD)) [1,2]; their occurrence has also been predicted recently for laser-assisted electron-atom scattering (LAES) [3]. Plateau effects are most pronounced for linear laser polarization, in which case the extent of the plateau regions (i.e.…”

“…The exact quantum results for the LAES and ATD amplitudes involve a sum of generalized Bessel functions multiplied by the Fourier-coeffi cients of f (t) [3,10]. For our purposes, it is convenient to represent these amplitudes in an equivalent form in terms of the following Fourier integral: (2) where c Pn (t) is the periodic (in time) part of the Volkov wavefunction at the origin, and where A(t) = Ḟ (t)/ω 2 , u p = F 2 /(2ω 2 ) and p n is a fi nal (detached or scattered) electron momen tum. As shown by an accurate quantum analysis of our exactly solvable 3D-model, plateau features in strong fi eld phenomena originate from those occurring in the spectra of the Fourier-coeffi cients of f(t), or, equivalently, of the Fourier-harmonics of Φ(r, t) near the origin (cf (1)).…”

Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields

“…For the simplest atomic system in nature, hydrogen, which has a binding energy of 13.6 eV, absorption of a single photon with an energy exceeding this value will induce direct breakup of the system. With increasing photon flux, additional photons can be absorbed, giving rise to multiphoton processes and above-threshold ionization (ATI) [1,2]. From perturbation theory calculations, a general increase in breakup probability with intensity of the imposed radiation field is expected.…”