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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.

Fivefold differential cross sections for electron-induced double ionization of isolated oriented water molecules are reported. The theoretical investigation is performed within the first Born approximation by describing the initial molecular state by means of single-center wave functions. The contributions of each final state to the double-ionization process, i.e., with target electrons ejected from similar and/or different molecular subshells, are studied and compared in terms of shape and magnitude. Furthermore, for the particular target orientations investigated, we identify clearly the signature of the main scenarios involved in (e,3e) reactions, namely, the shake-off and the two-step 1 mechanisms.

Theoretical doubly differential and total cross sections for electron-induced double ionization of oriented water molecules are reported here. The calculations are performed within the first Born approximation by describing the initial molecular state by means of single-center wave functions. Furthermore, the incident (scattered) electron is described by a plane wave while a Coulomb wave function is used for modeling the two secondary ejected electrons. The contribution of each final state to the double-ionization process is analyzed, namely, in considering target electrons ejected either from similar or from different molecular subshells. Thus, secondary electron energetic distributions as well as total cross sections are reported for particular target configurations, pointing out orientation effects in the double-ionization process