Single- and Multiple-Electron Removal Processes in Proton-Water Vapor Collisions*

Charge-state correlated cross sections for single- and multiple-electron removal processes due to capture and ionization in proton-$\rm H_2O$ collisions are calculated by using the non-perturbative basis generator method adapted for ion-molecule collisions [1]. Orbital-specific cross sections for vacancy production are evaluated using this method to predict the yields of charged fragments ($\rm H_2O^+, OH^+, H^+, O^+$) according to branching ratios known to be valid at high impact energies. At intermediate and low energies, we obtain fragmentation results on the basis of predicted multi-electron removal cross sections, and explain most of the available experimental data [2]. The cross sections for charge transfer and for ionization are also compared with recent multi-center classical-trajectory Monte Carlo calculations [3] for impact energies from 20keV to several MeV. \\[4pt] [1] H.J. L\"udde et al, Phys. Rev. A {\bf 80}, 060702(R) (2009)\\[0pt] [2] M. Murakami et al, to be submitted to Phys. Rev. A (2012)\\[0pt] [3] C. Illescas et al, Phys. Rev. A {\bf 83}, 052704 (2011)