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A: Fachverband Atomphysik
A 6: Interaction of matter with ions
A 6.6: Talk
Tuesday, March 11, 2008, 09:45–10:00, 3D
A critical test for distorted wave theories: laser-assisted single ionization by ion impact — •Marcelo Ciappina1 and Lars Bojer Madsen2 — 1Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, D-01187 Dresden, Germany — 2Department of Physics and Astronomy, Univ. of Aarhus, 8000 Aarhus C, Denmark
We study single ionization in laser-assisted high-energy non-relativistic ion-atom collisions and show that the low-energy angular differential electron spectrum may be enhanced significantly by a weak external field. With increasing the strength of the assisting field, the energy spectrum develops a plateau with a characteristic cut-off [1]. In the plateau region we predict distinct multiphoton peaks separated by the photon-energy of the laser field. In the present laser-assisted continuum-distorted-wave eikonal-initial-state (LA-CDW-EIS) theory, this effect may be related to the dynamics in the two-body electron-projectile subsystem. First-order type theories, e.g. the laser-assisted distorted wave Born (LA-DWB) [2] and first Born approximation (LA-FBA) [3], do not account for the phase-distortion of the target electron by the incoming projectile and consequently the associated plateau, cut-off and multiphoton features are absent. The combined process where an electron is ionized by a heavy ion and subsequently moves in the laser field and under the influence of the Coulomb fields of the projectile and the target represents a stringent test for distorted wave theories. [1] M. F. Ciappina and L. B. Madsen, Phys. Rev. A, (submitted). [2] ibid, J. Phys. B 39 5057 (2006). [3] A. Voitkiv and J. Ullrich, J. Phys. B 34 1673 (2001); ibid, 34 4383 (2001).