Electron impact dissociation of molecular ions

The ORNL Electron-Ion Crossed Beams Experiment is used to determine absolute cross sections for electron-impact dissociation of molecular ions. Investigations have been carried out on DCO$^{+}$, CH$_3^+ $, and N$_2 $D$^+$ cations, considered as amongst those species playing important roles in such diverse areas as laboratory plasmas, astrophysics, and thermonuclear fusion. The obtained results on dissociation of DCO$^{+}$ resulting in CO$^{+}$ fragments are discussed in light of the energy levels and photo-dissociation cross section of HCO$^{+ }$predicted by \textit{ab initio} multi-reference configuration interaction calculations [Koch et al, 1995 \textit{Ber. Bunsenges Phys. Chem.} \textbf{99} (3) 393]. Preliminary results on CH$_3^+ $ are compared to the measurements of Lecointre et al [\textit{XXIV ICPEAC, }Rosario, Argentina, 20 - 26 July 2005; (Poster Session)]. Results for dissociation of N$_2 $D$^+$ producing ND$^+$ are also presented.