ИСТИНА

When a molecule irradiated with an intense X-ray pulse like the ones generated by the modern free-electron lasers or synchrotron sources, the prime process to occur is photoeffect, followed by a complex evolution involving Auger-decay, fluorescence, vibration and dissociation. Finally the molecule obtains essential charge with further Coulomb explosion. For the processes occurring in high-frequency domain typically inner-shell ionization dominates over valence-shell, and as result exotic hollow states of the molecules such as SCH (single core-hole) and DCH (double core-hole) are created. Note that while ground states of H2O+, H2O2+ were explored in a very detail the investigation of these dications with 1s-vacancie(s) are very restricted. The lack of these data are caused by the problem with convergence for hollow states taking place in some numerical approaches. This work was stimulated by the recent investigation [1], where the moments of water decay fragments were measured in coincidence with Oxygen ion charge. Additionally measured values are charge distribution and kinetic energy release (KER). Calculations were performed by solving the system of classical dynamical equations with the surface of potential energy obtained by the original code [2]. We consider water molecule irradiated by the X-Ray pulse with frequency 1 KeV. After first inner-shell ionization there is a competition between subsequent Auger-decay and ionization. In first case H2O(z=+2) the ion relax to the equilibrium linear geometry; in second case there is no stable configuration and the ion decays (if ionization occurs from 1s shall) or dissociates (if ionization occurs form valence shell). Let us emphasize that opening the molecule is crucial to reproduce some experimental finding especially protons observed in the same hemiplane as oxygen ion.