Influence of the projectile charge sign in light particle single ionization of H2O

Abstract

Positron- and electron-impact ionization of the 1b1 and 3a1 orbitals of H2 O is studied by meansof the CDW-EIS model at an impact energy of 81 eV. Fully differential cross sections are calculated andcontrasted after a proper average procedure over molecular orientations. Double binary peaks are observedfor positron-impact and coplanar geometries, while only single binary peaks are exhibited for electron-impact ionization. For the denominated perpendicular planes, similar structures are observed, with anenhancement or decrease of the binary and recoil lobes. Forward electron emission is analysed identifyingthe electron capture to the continuum structure for positron-impact. A high narrow peak and a huge dipfor positron- and electron-impact are respectively observed, structures already seen in previous ionizationstudies involving both light and heavy projectiles.