Electron impact ionization of and : contributions from different dissociation channels of multiply ionized molecules

Abstract

The cross sections of ionic products due to the electron impact ionization of and have been measured for the electron energies from threshold up to 600 eV. The contributions to the cross sections from the possible reaction channels after the multiple ionization of molecules are also determined. The experiment shows that for both and the singly charged fragment or originates mainly from the contribution of the dissociation of the singly charged parent ions, whereas the doubly charged fragments or are mainly from the dissociation channel of doubly ionized into or into , respectively. At high electron energies, 85% of singly ionized molecules stabilize into , whereas about 70% of singly ionized molecules stabilize into . More than 80% of doubly ionized and molecules dissociate through the equal charge separation channel. However, after triple ionization, most of the molecules dissociate into two charged fragments. The experiment also shows that the total cross sections for the different ionization stages decrease exponentially as the ionization stage increases.