L-auger electron production in krypton ion-atom collisions

Secondary-electron production as a consequence of inner-shell vacancy decay for the Kr-Kr system has been studied. Electron-energy spectra differential in impact parameter were obtained by detecting electrons in coincidence with projectile ions scattered through a known angle. The spectra exhibit structure attributable to Auger decay of L-shell vacancies. The collision-energy dependence of the L-Auger yields is consistent with the L-shell excitation being due to rotational coupling of the 4fσ, 4fπ, 4fδ, 4f Phi orbitals of the Kr-Kr quasimolecule, as originally proposed by Shanker and coworkers. The L-Auger electron energies and relative transition-group intensities suggest that L-shell vacancy decay occurs in Kr ions with initial charge states greater than +10, indicating that a surprisingly large number of electrons are emitted prior to the decay of the L-shell vacancy. These prior ionizations, most of which occur during the collision, are the source of the 100-600 eV continuum electrons which dominate the low-energy region of the electron spectrum