Recent experiments on near-threshold electron-impact excitation of multiply charged ions

Conference · Wed Apr 01 04:00:00 EST 1998

OSTI ID:672024

Bannister, M E ^[1]; Djuric, N; Woitke, O; Dunn, G H ^[2]; Chung, Y S ^[3]; Smith, A C.H. ^[4]; Wallbank, B ^[5]

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1. Oak Ridge National Lab., TN (United States). Physics Div.
2. Univ. of Colorado, Boulder, CO (United States)
3. Chungnam National Univ., Daejon (Korea, Republic of). Dept. of Physics
4. University Coll. London (United Kingdom). Dept. of Physics and Astronomy
5. St. Francis Zavier Univ., Antigonish, Nova Scotia (Canada). Dept. of Physics

Some recent measurements of excitation of multiply charged ions by electrons studied in beam-beam experiments are highlighted. The emphasis is on absolute total cross sections measured with the merged electron-ion beams energy-loss (MEIBEL) technique, although some results obtained with the crossed-beams fluorescence method are also presented. The MEIBEL technique allows the investigation of optically-allowed and forbidden transitions with sufficient energy resolution, typically about 0.2 eV, to resolve resonance structures in the cross sections. Results from the JILA/ORNL MEIBEL experiment on dipole-allowed transitions in several ions demonstrate the success of various theoretical methods in predicting cross sections in the absence of resonances. Comparisons of R-matrix calculations and measured cross sections for spin-forbidden transitions in Mg-like Si{sup 2+} and Ar{sup 6+}, however, show that further refinements to the theory are needed in order to more accurately predict cross sections involving significant contributions from dielectric resonance`s and interactions between neighboring resonances.

• Research Organization: Oak Ridge National Lab., Physics Div., TN (United States); National Inst. of Standards and Technology, Boulder, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States)
• DOE Contract Number: AC05-96OR22464; AI05-86ER53237
• OSTI ID: 672024
• Report Number(s): ORNL/CP--97360; CONF-980365--; ON: DE98004882; BR: AT5030100
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ARGON IONS
ELECTRON-ION COLLISIONS
EXCITATION
FORBIDDEN TRANSITIONS
MULTICHARGED IONS
R MATRIX
SILICON IONS
TOTAL CROSS SECTIONS