Saddle-point shifts in ionizing collisions

Abstract

Experimental studies of electrons ejected in ionizing collisions between ${\mathrm{C}}^{+}$, ${\mathrm{C}}^{2+}$, and ${\mathrm{C}}^{3+}$ projectiles and He and Ne targets have been made for incident projectile energies of 83, 100, and 150 keV/u. The data exhibit pronounced maxima in the 10\ifmmode^\circ\else\textdegree\fi{} ejected-electron energy spectra and projectile-charge-dependent shifts of these maxima which strongly supports the hypothesis of an independent ``saddle-point'' ionization mechanism. A possible cause of disagreement between these results and existing experimental data is also discussed.