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

Positron- and electron-impact ionization of the 1b1 and 3a1 orbitals of H2O is studied by means of the CDW-EIS model at an impact energy of 81 eV. Fully differential cross sections are calculated and contrasted after a proper average procedure over molecular orientations. Double binary peaks are observed for 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 an enhancement or decrease of the binary and recoil lobes. Forward electron emission is analysed identifying the electron capture to the continuum structure for positron-impact. A high narrow peak and a huge dip for positron- and electron-impact are respectively observed, structures already seen in previous ionization studies involving both light and heavy projectiles