Diffraction electron-atom scattering in an intense low-frequency laser field

Abstract

An explanation of discrepancies between predictions of the Kroll-Watson theory and cross sections measured in the Wallbank-Holmes experiments on electron-atom scattering in the presence of a powerful lowfrequency laser field is presented. Our model calculations for helium and argon as target atoms come out to be in good agreement with experimental results; i.e., obtained cross sections are by many orders of magnitude larger than those predicted by the Kroll-Watson theory. A mechanism responsible for such a substantial increase of the calculated cross sections is found to be due to the diffraction scattering of electrons by atomic obstacles. ͓S1050-2947͑97͒50912-7͔ PACS number͑s͒: 34.50.Rk, 32.80.Ϫt, 03.65.Nk RAPID COMMUNICATIONS R4396 56 A. JAROŃ AND J. Z. KAMIŃ SKI

Laser-assisted electron-argon scattering at small angles

“…Their result for two photon exchange is several orders of magnitude higher, however. This may be due to a convergence issue, as a group using a similar method for laser-assisted helium scattering at first found high cross sections [11], but later found better results that are closer to the KWA [18].…”

“…)It can be shown that the first variation δb[Ψ β ] vanishes for all deviations δΨ from the exact solution. To show this, integrate by parts and use the periodicity restriction(11) on the energy operator. δ Σ,T…”

“…Sun et al [10] apply the second Born approximation. Jaroń and Kamiński [11,12] also use a similar off-shell approximation. They suggest that a diffraction effect due to a long range potential, i.e.…”

Laser-Assisted Elastic Electron Scattering from Argon

“…Chen and Robicheaux [8] made use of an approximate version of the Floquet R-matrix method to calculate one-and twophoton emission and absorption cross sections and found their results, which were the same as the KWA, differed from the experimental results. Jaron and Kaminski [9] found it was important for small-angle scattering to take into account the effect of the polarization potential. But Milosevic and Ehlotzky [10] were ignored it.…”

Off-shell effects in laser-assisted scattering

“…To understand this discrepancy, polarization of the target atom has been studied but shown to have negligible effect [10,13,14]. The theoretical work also involves distorted-wave [12,15,16], Floquet close-coupling [17], R-matrix Floquet [18] and Floquet Lippman-Schwinger [19,20] methods as well as evaluation of the impulse approximation [12,21]. A clear explanation of the experimental results has not yet emerged.…”