Interference effects in the ionization of H2 by fast charged projectiles

A theoretical investigation of the experimentally observed (Stolterfoht N et al 2001 Phys. Rev. Lett. 87 023201) interference effects in the double differential cross sections for ionization of the hydrogen molecule by fast ion impact is reported. The H-2/2H cross section ratios as a function of the ejected electron velocity show an oscillating pattern, for which Stolterfoht et al propose a formula C + G sin (k D)/k D), where k is the electron momentum and D the internuclear separation in H-2. Our analysis in its simplest form leads instead to a formula C + G sin(k(parallel to) D)/(k(parallel to) D) where k(parallel to) is the component of k parallel to the projectile velocity. The presented theoretical model thus explains why at 90degrees the interference pattern will be strongly suppressed. In addition to the simplified analysis a numerical evaluation of a more accurate model is presented, confirming the latter qualitative prediction.