Laser-assisted ion-atom collisions: Plateau, cutoff, and multiphoton peaks
Marcelo F. Ciappina and Lars Bojer Madsen

We study ionization in laser-assisted high-energy non-relativistic ion-atom collisions and show that the low-energy angular differential electron spectrum may be enhanced by 5 orders of magnitude by an external field of strength less than 1/100 of the atomic field. With increasing strength of the assisting field, the energy spectrum develops a plateau with a characteristic cut-off. In the plateau region we predict distinct multiphoton peaks separated by the photon-energy of the assisting 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. The laser-assisted distorted wave Born (LA-DWB) and first Born approximation (LA-FBA) 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 not predicted by these theories.

© 2008 The American Physical Society.