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Partial photoionization cross sections and photoelectron angular distributions for double excitations up to the {ital N}=5 threshold in helium

Journal Article · · Physical Review A
; ; ;  [1];  [2]
  1. Department of Physics, University of Central Florida, Orlando, Florida 32816-2385 (United States)
  2. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6201 (United States)
Partial photoionization cross sections {sigma}{sub {ital n}} and photoelectron angular distributions {beta}{sub {ital n}} were measured for all possible final ionic states He{sup +}({ital n}) in the region of the double excitations {ital N}({ital K},{ital T}){sup {ital A}} up to the {ital N}=5 threshold. At a photon energy bandpass of 12 meV below the thresholds {ital N}=3,4, and 5, this level of differentiation offers the most critical assessment of the dynamics of the two-electron excitations to date. The experimental data are very well described by the most advanced theoretical calculations. Weaker double-excitation series with {ital K}={ital N}{minus}4 are clearly visible in the {beta}{sub {ital n}} data, and even previously unobserved extremely weak series members with {ital A}={minus}1 can be discerned, showing the high sensitivity of the angular resolved measurements. The shapes of the resonance-induced variations of {sigma}{sub {ital n}} or {beta}{sub {ital n}} in the double excitations below a given threshold {ital N} change radically depending on the final ionic state {ital n} but display striking similarities when comparing the satellite states with {ital n}={ital N}{minus}1 and {ital n}={ital N}{minus}2 below each threshold {ital N}. These systematic patterns may indicate a general rule for the underlying two-electron dynamics. {copyright} {ital 1996 The American Physical Society.}
Research Organization:
Lawrence Berkeley National Laboratory
DOE Contract Number:
AC03-76SF00098
OSTI ID:
383522
Journal Information:
Physical Review A, Journal Name: Physical Review A Journal Issue: 3 Vol. 54; ISSN 1050-2947; ISSN PLRAAN
Country of Publication:
United States
Language:
English

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