Confinement effects on the electron transfer cross section: a study of He2+ colliding on atomic H

Abstract

In this work, the role of pressure produced by the surrounding conditions of neighboring atoms on the charge transfer cross section in the interaction of ions with atoms is studied. The effect of pressure on the target is simulated by a spherical confinement cavity model with the target atom at its center. The electron transfer probability is obtained by a time-dependent solution to the Schrödinger equation by means of a finite-difference approach and the Crank–Nicolson propagation method. Results are presented for the benchmark system HeH() under different confinement conditions. Within this first-order approach to pressure effects, it is found that the radial region of the electron capture probability is affected by the cavity, meanwhile the rotational part of the interaction is only slightly modified. Furthermore, Stückelberg oscillations are preserved as a function of the impact parameter and only its intensity is reduced with a slight shift towards low impact parameters as pressure is increased. The pressure effect is larger when the electron interaction on the target is restricted to within the cavity than when it acts also outside the cavity. In addition, the larger the pressure, the smaller the electron capture cross section. The numerical results are interpreted by an analytic two-state model that supports the numerical findings.