T. Stohlker et al., K-SHELL EXCITATION STUDIED FOR H-LIKE AND HE-LIKE BISMUTH IONS IN COLLISIONS WITH LOW-Z TARGET ATOMS, Physical review. A, 57(2), 1998, pp. 845-854
The formation of excited projectile states via Coulomb excitation is i
nvestigated for hydrogenlike and heliumlike bismuth projectiles (Z = 8
3) in relativistic ion-atom collisions; The excitation process was una
mbiguously identified by observing the radiative decay of the excited
levels to the vacant Is shell in coincidence with ions that did not un
dergo charge exchange in the reaction target. In particular, owing to
the large fine-structure splitting of Bi, the excitation cross section
s to the various L-shell sublevels are determined separately. The resu
lts are compared with detailed relativistic calculations, showing that
both the relativistic character of the bound-state wave functions and
the magnetic interaction are of considerable importance for the K-she
ll excitation process in high-Z ions such as Bi, The experimental data
confirm the result of the complete relativistic calculations, namely,
that the magnetic part of the Lienard-Wiechert interaction leads to a
significant reduction of the K-shell excitation cross section. [S1050
-2947(98)00801-4].