Distorted-wave calculations of the electron-impact ionization of highly ionized Na-like ions

Journal Article · Thu Oct 15 00:00:00 EDT 1987 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.36.3642· OSTI ID:6363172

Griffin, D C; Pindzola, M S; Bottcher, C

We report on distorted-wave calculations of the electron-impact ionization cross sections and rate coefficients for the Na-like ions Ti/sup 11+/, Cr/sup 13+/, Fe/sup 15+/, and Ni/sup 17+/. The cross sections for direct ionization out of the 3s, 2p, and 2s subshells were determined using the configuration-average, distorted-wave approximation. In addition, excitation-autoionization contributions originating from inner-shell excitations of the type 2s/sup 2/2p/sup 6/3s..-->..2s/sup 2/2p/sup 5/3snl (n = 3,4,5) and 2s/sup 2/2p/sup 6/3s ..-->..2s2p/sup 6/3snl (n = 3,4) were calculated by employing the distorted-wave approximation and configuration-interaction, bound-state wave functions. Near threshold, the total-ionization cross sections in all four ions are enhanced by approximately a factor of 5 through excitation autoionization. These excitation-autoionization contributions are large, even though they have been substantially reduced by radiative decay to the bound states of the initial ion. Furthermore, although electron correlation has a minimal effect on the excitation cross sections, the magnitude of the branching ratios for autoionization is quite sensitive to configuration interaction in the autoionizing levels. This is especially true for the 2p..-->..3d excitations, where configuration interaction between 2p/sup 5/3s3d and 2p/sup 5/3p/sup 2/ can increase the magnitude of the autoionizing rates for levels within the 2p/sup 5/3s3d configuration by as much as three orders of magnitude. Thus, for example, in the case of the 2p..-->..3d excitation in Ni/sup 17+/, correlation increases the overall branching ratio for autoionization from 0.27 to 0.53.

• Research Organization: Joint Institute for Laboratory Astrophysics, University of Colorado National Bureau of Standards, Boulder, Colorado 80309
• OSTI ID: 6363172
• Journal Information: Phys. Rev. A; (United States), Vol. 36:8
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
CHROMIUM IONS
ELECTRON-ION COLLISIONS
IRON IONS
NICKEL IONS
TITANIUM IONS
AUGMENTATION
AUTOIONIZATION
CROSS SECTIONS
DISTORTED WAVE THEORY
IONIZATION
CHARGED PARTICLES
COLLISIONS
ELECTRON COLLISIONS
ION COLLISIONS
IONS
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena