3D Imaging of the Collision-Induced Coulomb Fragmentation of Water Molecules

The multiple ionization and fragmentation of H₂O by fast H⁺ and He⁺ ions was studied using a position- and time-sensitive multiparticle detector. By the coincident measurement of correlated fragment momenta a complete three-dimensional image of the breakup process can be obtained for each individual event. Of special interest is the process H₂O→H⁺+H⁺+O⁺ where a simple Coulomb explosion model is insufficient to explain the measured fragmentation energies and angular correlations. Better agreement is achieved with ab initio multiconfiguration self-consistent field calculations of the intermediate H₂O³⁺ parent ion.