Independent-atom-model description of multiple ionization of water, methane, and ammonia molecules by proton impact

We study multiple ionization in proton collisions with water, methane, and ammonia molecules using an independent-atom model. Previous work on total (net) capture cross sections is extended to treat the multiple-ionization channels explicitly. present theoretical framework charge-state correlated processes within independent-atom-model approach, which uses geometric screening introduced for different molecular geometries orientations. A comparison of results made target ${\text{H}}_{2}\text{O}, {\text{CH}}_{4}$, ${\text{NH}}_{3}$ emphasis $q$-fold electron removal. Coincident measurements produced fragments can be used estimate this quantity. find very good agreement model calculations water molecule, where data exist $q=1--4$. For methane we observe reasonable $q=1,2$ only $q=1$, i.e., experimental show little support a direct channel latter case.