The dependence of the forward-backward asymmetry parameter on the molecular orientation in angular distributions of emitted electrons in the H2 ionisation induced by bare ion impact

We have studied the angular distributions of electron emission in collisions of bare ions with H2 oriented target using molecular wave functions calculated with the Schwinger variational iteractive method within the Continuum Distorted Wave-Eikonal Initial State approximation (CDW-EIS-SVIM). By calculating the forward-backward asymmetry parameter for different molecular orientations we show that this parameter depend not only on the perturbation strength, S p = Z p / v p , where Z p and v p are respectively the projectile charge and velocity (two-centre effect) and on the outgoing electron velocity, but may also depend on how the molecule is aligned with respect to the projectile incident axis. Doubly differential cross sections (DDCS) for fixed in space molecular target were calculated. The asymmetry parameter was compared with both experimental and theoretical orientation averaged results.