Selective production of Li-, Be-, and B-likeKvacancy states in fast Ne projectiles studied by zero-degree Auger spectroscopy

High-resolution measurements of Ne K Auger electrons have been performed using multiply charged ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ projectiles in collisions with He, ${\mathrm{CH}}_4$, and Ar at impact energies of 70 and 100 MeV. Kinematic line-broadening effects were substantially reduced by observing the electrons at 0° with respect to the beam axis. For the He-gas target the outer-shell electronic configuration of the incident ions is essentially retained during K-shell ionization. Thus, B-, Be-, and Li-like electron configurations were selectively produced for incident ions of ${\mathrm{Ne}}^{4+}$, ${\mathrm{Ne}}^{5+}$, and ${\mathrm{Ne}}^{6+}$, respectively. For target gases ${\mathrm{CH}}_4$ and Ar, Li-like lines are found to be strongly excited, independent of the initial charge state of the projectiles.