Young-type interference effects in heavy-ion collisions with diatomic molecules

Abstract

Coherent electron emission from molecular targets has been a subject of main interest in atomic collisions stimulated by the work of 1966 by Cohen and Fano [1]. They theoretically obtained that oscillation patterns should appeared in photoionization cross sections of nitrogen and oxygen molecules. Their comparison with experimental data seemed to confirm their prediction. However, clear evidence of the effect was given only 35 years later, when interferences were experimentally found in double differential cross sections of electron ionization of hydrogen molecules impacted by fast Kr ions [2]. Electrons are emitted coherently like from the proximities of both molecular centers in phase or out of phase, producing thus an oscillatory behavior of the resulting spectra. The analogy with the Young two-slit experiment was immediate. In the case of our interest, electrons are not scattered from the molecular centers but emitted from them. Following reference [2], numerous studies were developed showing an incessant activity in the field. They were possible due to the seminal advance of experimental capabilities, which allows nowadays the feasibility of kinematically complete experiments. We will focus our interest mainly on the contributions of the present author (reading of a review article by Ciappina et al. [3] is recommended), in particular where the Continuum Distorted Wave Eikonal Initial State model was employed. Within this theoretical description, for enough fast projectiles, the collision time was considered to be smaller than the vibrational and rotational molecular ones, so that the target was supposed as fixed in its original position during all the reaction. Moreover, the process was reduced to a one active electron, assuming that the passive electrons (the ones that remain bound to the target) stay as frozen in their initial orbitals. A two-effective center approximation