Theoretical description of high-lying two-electrons states

Conference · Thu Jun 10 00:00:00 EDT 1993 · AIP Conference Proceedings (American Institute of Physics); (United States)

OSTI ID:6024326

Greene, C H ^[1]; Cavagnero, M ^[2]; Sadeghpour, H R ^[3]

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1. Department of Physics and Joint Institute for Laboratory Astrophysics University of Colorado, Boulder, Colorado 80309-0440 (United States)
2. Department of Physics and Astronomy University of Kentucky, Lexington, Kentucky 40506-0055 (United States)
3. Harvard-Smithsonian Center for Astrophysics 60 Garden Street, Cambridge, Massachusetts 02138 (United States)

Within the past two years, experiments on high-lying doubly-excited states in He and H[minus] have shown spectra at energies near excited hydrogenic thresholds having principal quantum numbers in the range [ital N]=5--9. While they display some nontrivial complexities, the spectra are tremendously simpler than might be anticipated on the basis of independent electron models, in that only a small fraction of the total number of anticipated resonances are observed experimentally. Moreover, for principal quantum number [ital N] that are not too high, specifically [ital N][lt]5 in He and [ital N][lt]10 in H[sup [minus]], the resonance positions are described accurately by adiabatic calculations using hyperspherical coordinates and can be parametrized by a remarkably simple two-electron Rydberg formula. The observed propensity for excitation of only a small subset of the possible resonance states has been codified by several groups into approximate selection rules based on alternative (but apparently equivalent) classification schemes. Comparatively few attempts have been made at quantitative tests of the validity of these rules. The present review describes recent efforts to quantify their accuracy and limitations using R-matrix and quantum defect techniques, and Smith's delay-time matrix. Prospensity rules for exciting different degrees of freedom are found to differ greatly in their degree of validity.

• OSTI ID: 6024326
• Report Number(s): CONF-920840--
• Journal Information: AIP Conference Proceedings (American Institute of Physics); (United States), Journal Name: AIP Conference Proceedings (American Institute of Physics); (United States) Vol. 275:1; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

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COULOMB FIELD
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ELECTRONS
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