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- ItemAttosecond electron thermalization in laser-induced nonsequential multiple ionization: Hard versus glancing collisions(College Park, MD : Institute of Physics Publishing, 2008) Liu, X.; De Morisson Faria, C.F.; Becker, W.A recollision-based largely classical statistical model of laser-induced nonsequential multiple (N-fold) ionization of atoms is further explored. Upon its return to the ionic core, the first-ionized electron interacts with the other N - 1 bound electrons either through a contact or a Coulomb interaction. The returning electron may leave either immediately after this interaction or join the other electrons to form a thermalized complex which leaves the ion after the delay Δt, which is the sum of a thermalization time and a possible additional dwell time. Good agreement with the available triple and quadruple ionization data in neon and argon is obtained with the contact scenario and delays of Δt = 0.17 T and 0.265 T, respectively, with T the laser period. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
- ItemInterference in strong-field ionization of a two-centre atomic system(College Park, MD : Institute of Physics Publishing, 2008) Ansari, Z.; Böttcher, M.; Manschwetus, B.; Rottke, H.; Sandner, W.; Verhoef, A.; Lezius, M.; Paulus, G.G.; Saenz, A.; Milošević, D.B.Strong-field photoionization of argon dimers by a few-cycle laser pulse is investigated using electron-ion coincidence momentum spectroscopy. The momentum distribution of the photoelectrons exhibits interference due to the emission from the two atomic argon centres, in analogy with a Young's doubleslit experiment. However, a simulation of the dimer photoelectron momentum spectrum based on the atomic spectrum supplemented with a theoretically derived interference term leads to distinct deviations from the experimental result. The deviations may have their origin in a complex electron dynamics during strong-field ionization of the Ar2 dimer. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
- ItemInterference structure of above-threshold ionization versus above-threshold detachment(Bristol : IOP, 2012) Korneev, Ph.A.; Popruzhenko, S.V.; Goreslavski, S.P.; Becker, W.; Paulus, G.G.; Fetić, B.; Milošević, D.B.Laser-induced electron detachment or ionization of atoms and negative ions is considered. In the context of the saddle-point evaluation of the strong-field approximation (SFA), the velocity maps of the direct electrons (those that do not undergo rescattering) exhibit a characteristic structure due to the constructive and destructive interference of electrons liberated from their parent atoms/ions within certain windows of time. This structure is defined by the above-threshold ionization rings at fixed electron energy and by two sets of curves in momentum space on which destructive interference occurs. The spectra obtained with the SFA are compared with those obtained by numerical solution of the time-dependent Schrödinger equation. For detachment, the agreement is excellent. For ionization, the effect of the Coulomb field is most pronounced for electrons emitted in a direction close to laser polarization, while for nearperpendicular emission the qualitative appearance of the spectrum is unaffected.