Electron-impact ionization of Sm¹²⁺ ions: Resonances far beyond threshold

MITNIK, D. M.; GRIFFIN, D. C.; COLGAN, J.; PINDZOLA, M. S.; AICHELE, K.; ARNOLD, W.;HATHIRAMANI, D.; SCHEUERMANN, F.; SALZBORN, E.

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

The American Physical Society

Año: 2001 vol. 64 p. 62705 - 62725

1050-2947

Unusual resonance features at high energies were recently discovered in the experimental crossed-beams measurements of the electron-impact ionization of Sm12+. Theoretical calculations were able to confirm that they are due to deep-core excitation with capture into dielectronic states followed by sequential double Auger decay [K. Aichele et al., Phys. Rev. Lett. 86, 620 (2001)]. In this paper additional experimental results are presented, showing more resonances in the single-ionization cross section. Detailed level-to-level calculations of dielectronic capture provide a clear identification of these resonances, as produced by a 3d-4f excitation with capture to different nl orbitals followed by sequential emission of two electrons. By using configuration-average distorted-wave calculations, we estimate the branching ratios for single and double ionization by considering the possible autoionization paths leading to resonant contributions to excitation, single ionization, and double ionization.