Electron-impact excitation along an isoelectronic sequence: B-like ions

Journal Article · Sat Oct 01 00:00:00 EDT 1994 · Physical Review A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.50.3105· OSTI ID:6952874

Zhang, H L; Pradhan, A K ^[1]

---

1. Department of Astronomy, Ohio State University, Columbus, Ohio 43210 (United States)

A systematic study of collision strengths for the electron-impact excitation of ions along an isoelec- tronic sequence is presented. 105 excitation transitions between 15 fine-structure levels of the eight [ital LS] terms 2[ital s][sup 2]2[ital p]([sup 2][ital P][sup [ital o]]), 2[ital s]2[ital p][sup 2]([sup 4][ital P],[sup 2][ital D],[sup 2][ital S],[sup 2][ital P]), and 2[ital p][sup 3]([sup 4][ital S][sup [ital o]],[sup 2][ital D][sup [ital o]],[sup 2][ital P][sup [ital o]]) in boronlike ions are considered. The calculations include O IV, Ne VI, Mg VIII, Al IX, Si X, S XII, Ar XIV, Ca XVI, and Fe XXII in an eight-term close-coupling expansion, using the [ital R]-matrix method [H. L. Zhang, M. Graziani, and A. K. Pradhan, Astron. Astrophys. 283, 319 (1994)]. An 11-term expansion, including some [ital n]=3 states, is also carried out for Ne VI to study the effect of the coupling to higher-[ital n] complexes. The results were compared with those with a fully relativistic distorted-wave method by Zhang and Sampson [At. Data Nucl. Data Tables 56, 41 (1994)]. The study shows that the coupling effects and the resonance effects are still pronounced for highly charged ions, even up to Fe XXII. The relativistic effects, which are incorporated into the [ital R]-matrix calculations through the term-coupling method [W. Eissner, M. Jones, and H. Nussbaumer, Comput. Phys. Commun. 8, 270 (1974)], begin to manifest themselves for [ital Z][ge]16. This study should provide some guidelines for future [ital R]-matrix calculations for other isoelectronic sequences.

• OSTI ID: 6952874
• Journal Information: Physical Review A; (United States), Vol. 50:4; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
MULTICHARGED IONS
ELECTRON-ION COLLISIONS
BORON IONS
CROSS SECTIONS
ENERGY-LEVEL TRANSITIONS
EXCITATION
ISOELECTRONIC ATOMS
R MATRIX
RESONANCE
ATOMS
CHARGED PARTICLES
COLLISIONS
ELECTRON COLLISIONS
ION COLLISIONS
IONS
MATRICES
664300* - Atomic & Molecular Physics- Collision Phenomena- (1992-)