Monoelectronic and dielectronic processes producing K-shell vacancies in slow Neq+ + CH4 collisions (q=3–9)
Résumé
Cross sections for Auger emission following the creation of a K-shell vacancy in C have been measured in slow collisions of Neq+ with CH4 (q=3–9). Projectile energies ranging from 30 to 180 keV were investigated. For projectile charges lower than 7, the transfer of a K electron from C into the projectile is attributed to monoelectronic 2pσ−2pπ transitions induced by rotational coupling at small internuclear distances. For higher charge states, the measured cross sections are found to be significantly larger at the lowest projectile energies than predicted cross sections for 2pσ−2pπ transitions. It is shown that other mechanisms must be invoked, such as dielectronic excitation due to electron-electron interaction. Dielectronic excitation gives rise to a simultaneous transfer of inner- and outer-shell electrons of CH4 into a 2l shell of Ne.