Db. Milosevic et F. Ehlotzky, OFF-SHELL LOW-FREQUENCY APPROXIMATION FOR POTENTIAL SCATTERING IN A LASER FIELD - COMPARISON WITH THE WALLBANK AND HOLMES EXPERIMENTS, Journal of physics. B, Atomic molecular and optical physics, 30(13), 1997, pp. 2999-3007
We investigate the influence of the off-shell effects on the scatterin
g processes in the presence of a laser field in view of the recent exp
eriments by Wallbank and Holmes. In these experiments a large discrepa
ncy between the observed data for small-angle scattering and the on-sh
ell Kroll-Watson formula was reported. We show in the present work tha
t the off-shell effects are not responsible for this discrepancy by pr
esenting results for the differential cross sections obtained, using t
he off-shell low-frequency approximation and the [1, 1] Pade approxima
tion. We model the scattering from helium and argon atoms by the scatt
ering on a Yukawa-type potential. We show, using some examples, that h
igher laser field frequencies and intensities are necessary for obtain
ing observable off-shell-effects. We also comment on possibilities of
explaining the Wallbank and Holmes results. For one of these possibili
ties-double scattering-we compute, using our simple model, the relativ
e differential cross sections and obtain a qualitative agreement with
the experiments of Wallbank and Holmes, both for helium and argon.