Molecular orientation effect on the differential cross sections for the electron-impact double ionization of oriented water molecules

Abstract

Double ionization of isolated water molecules fixed in space is here investigated in a theoretical approach based on the first Born approximation. Secondary electron angular distributions are reported for particular (e,3e) kinematical conditions and compared in terms of shape and magnitude. Strong dependence of the fivefold differential cross sections on the molecular target orientation is clearly observed in (e,3-1e) as well as (e,3e) channels. Furthermore, for the major part of the kinematics considered, we identified the different mechanisms involved in the double ionization of water molecule, namely, the direct shake-off process as well as the two-step1 process. They are both discussed and analyzed with respect to the molecular target orientation.

Time-dependent density-functional-theory investigation of the collisions of protons and α particles with uracil and adenine

“…[103]) on DNA and RNA, since there is evidence that free secondary electrons cause significant single-and double-strand breaks in Deoxyribonucleic Acid (DNA) [4][5][6][7]104]. The calculated EC branching ratio for three for carbon-carbon bond impact points for protons incident on uracil, the average of 200 random impact points and incidence angles, also shown are experimental data taken from Ref.…”

Fivefold differential cross sections for electron-induced double ionization of outer and inner valence (1t2 and 2a1) molecular orbitals of CH4

“…Note that the summation over the index j considers only the five final states of the doubly ionized molecule, namely, those corresponding to the ejection of two electrons from the same molecular orbital. Moreover, as underlined in our previous works [34,35], the above-cited wave functions j (r) refer to a particular orientation of the molecular target given by the Euler angles (˛,ˇ, ). Thus, the 5DCSs calculated under these conditions refer to the double ionization of an oriented methane molecule, the transition matrix element T j being obviously dependent of the target, namely,…”

“…The latter may be taken as either equal to the value of the residual asymptotic nuclear charge (Z 1 = Z 2 = 2) or as dependent of the different moments k s , k 1 , and k 2 as reported by Berakdar [55] or Zhang [56] for (e,2e) experiments, and more recently by El Azzouzi et al [24] for (e,3e) collisions. In the current work, we have chosen the constant case as in our previous studies on double ionization of water molecule [34,35].…”

“…In this context, the current work aims at extending our model previously tested on water molecule [34,35] to the methane molecular target. Fivefold differential cross sections (5DCS) are then reported within the first Born approximation.…”

“…Finally, let us mention the first Born approximation (FBA), which is up to now the only theoretical model able to treat heavier molecular targets (for more details we refer the interested reader to Refs. [32][33][34][35] dedicated to the water double ionization). In this approach, each ejected electron is described by a Coulomb wave, the repulsion between the two ejected electrons being taken into account via the inclusion of a Gamow factor.…”