The role of multiple electron processes for fast ion H2O collisions

N. BACHI; R. E. OLSON; S. OTRANTO; G.S. OTERO

Grapevine, Texas, USA

Conferencia; 25th International Conference on the Application of Accelerators in Research and Industry (CAARI 2018); 2018

University of North Texas,

A new semiclassical model has been developed to investigate multiple ionization processes for collisions involving H+, C6+,O 8+and Si13+ ions with H2O molecules at intermediate impact energies. This model is based on quantum mechanicalmolecular structure calculations for water and its ionized components. The H2O molecule has been described as consistingof the 8 electrons of the valence molecular orbitals within a 3-center water target framework. Collisions with ions arepropagated using the classical trajectory Monte Carlo method and a dynamic change of the electrons' binding energies isincluded during ionizing collisions. The present model combines two desirable properties of the well-establishedindependent electron method (IE) and the sequential model (SE). These are the correct electron density associated to thevalence electrons of the former and the correct energy deposition in processes involving multiple electron removal of thelatter.The obtained cross sections for net and multiple ionization and single differential cross sections in energy and angle arebenchmarked against the experimental data reported in the literature and compared to the predictions of the IE and SEmethods.The advantages and limitations of the new procedure are discussed together with its potential extension to more complextargets.