Monoelectronic and dielectronic processes producing K-shell vacancies in slow Neq++CH4 collisions (q=3-9)

Cross sections for Auger emission following the creation of a K-shell vacan cy in C have been measured. in slow collisions of Neq+ with CH4 (q = 3-9). Projectile energies ranging from 30 to 180 keV were investi gated. For proj ectile charges lower than 7, the transfer of a K electron from C into the p rojectile is attributed to monoelectronic 2p sigma-2p pi transitions induce d by rotational coupling at small internuclear distances. For higher charge states, the measured cross sections are found to be significantly larger a t the lowest projectile energies than predicted cross sections for 2p sigma -2p pi transitions. It is shown that other mechanisms must be invoked, such as dielectronic excitation due to electron-electron interaction. Dielectro nic excitation gives rise to a simultaneous transfer of inner- and outer-sh ell electrons of CH4 into a 2l shell of Ne. [S1050-2947(99)06511-7].