Angular momentum distributions of Rydberg state electrons of Be-like sulfur produced through foil penetration

Spectra for Coster-Kronig (C-K) transition Is(2) 2p(P-2(3/2))9l --> Is(2) 2s (S-2(1/2))epsilonl' of Be-like S12+ ions produced following penetration of 2.5 MeV/u Sq+ ions (q = 7, 10, 12, 13) through C-foil targets of various thickness (1-6.9 mug/cm(2)) have been probed using zero-degree electron spectroscopy. It has been found that in collisions for Sq+ (q = 7, 10) ion incidence, in which the C-K electrons originate from the projectile bound electrons, a fraction of the angular momentum l = 1 of the Rydberg state decreases, and fractions of higher (l greater than or equal to 2) angular momenta increase, while the total intensity of the C-K electrons grows, as target foil thickness increases. The electron spectra for Sq+ (q = 13) incident ions, in which the autoionizing Be-like state is preferably formed by electron capture from the target continuum upon or near the exiting surface, do not change in l-distribution or intensity. The shift to higher l comes from the multiple collisions of electron with the target, in traveling at the same speed under the strong Coulomb potential of the projectile. The observed dependence of the l-distribution and the intensity of the Rydberg state on projectile initial charge and target thickness indicates the importance of transport phenomena for both the S13+ core and the projectile-entrained electrons inside solid. (C) 2002 Elsevier Science B.V. All rights reserved.