Multicenter description of the electron-impact ionization of aligned H2 molecules

E. ACEBAL; S. OTRANTO

Conferencia; Virtual International Conference on Photonic, Electronic and Atomic Collisions 2021; 2021

The electron-impact ionization of atoms andmolecules has represented a challenging field fordecades. Regarding fully differential studies,since the mid 1990s the introduction of reactionmicroscopes has allowed for an unprecedented ex-perimental level of detail. Concerning simple tar-gets, and from a theoretical point of view, theexperimental structures were accurately repro-duced by numerical intensive treatments and per-turbative methods, but the extension to complexmolecular targets is far from being understood.In this sense, we have recently introduceda multicenter CDW-EIS model, which, unlikethe usual CDW-EIS model, explicitly considersthe multicenter nature of the recoiling molecularion in the final-state wave function [1]. Withinthis formalism, we have performed calculationsof fully differential cross sections for the singleionization of aligned H 2 molecules at an impactenergy of 54 eV, and benchmarked our results tothe recent experimental data from Ren et al. [2]and other theoretical methods used to describethese data, such as the TDCC method.In this work, we present the calculations re-garding this collision system by means of threedifferent models within the CDW-EIS formalism.The first one considers the residual ion as a sin-gle center of charge Z = +1 (1C), the secondone incorporates the multicenter nature of thetarget by neglecting the remaining-electron re-pulsive potential terms (2C), and the third oneaccounts for the complete anysotropic nature ofthe molecular ion (MC).In Figure 1, we contrast our results with theexperimental data and the numerical intensiveTDCC method as a function of the emission an-gle of one electron into the perpendicular xyplane and for equal energy sharing and a partic-ular orientation of the target. It can be seen thatthe MC model correctly reproduces the peaks po-sitions along the direction of the atoms? positions(light gray dashed vertical lines in Figure 1), incontrast to other theories.We also present calculations for six more ge-ometries rotating the molecular target and, in ad-dition, we analyse the FDCS as a function of theangle between the continuum electron momentak 1 and k 2 , a representation to which not muchattention has been paid so far for these data.References[1] Acebal E and Otranto S 2020 Phys. Rev. A 102042808[2] Ren X et al 2012 Phys. Rev. Lett. 109 123202