One- and two-electron excitations of helium in the [ital s]-wave model

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Physical Review A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.50.3793· OSTI ID:7122272

Draeger, M; Handke, G; Ihra, W; Friedrich, H ^[1]

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1. Physik Department, Technische Universitaet Muenchen, 85747 Garching (Germany)

The energies of the bound states and energies and widths of autoionizing resonant states of helium are calculated within the [ital s]-wave model, where the individual orbital angular momenta of both electrons are zero. The energies of the bound 1[ital sns] states differ from the corresponding energies in real helium only via a small [ital n]-independent shift [Delta][mu] in the quantum defects, which amounts to [Delta][mu]=0.011 for singlet states and [Delta][mu]=0.004 for triplet states. The quantum defects of more than 50 bound and resonant states with singlet or triplet symmetry are reproduced by an empirical four-parameter formula to within an rms deviation of less than 0.016. The normalized widths of the autoionizing [ital Nsns] resonant states increase with the smaller quantum number [ital N], and the widths of the singlet states tend to become larger than the separation of successive resonances in the Rydberg series for [ital N][approx]8. Effects of interference of Rydberg series can be described in the framework of multichannel quantum-defect theory. In the 7[ital sns] singlet series of resonances, interference due to the 8[ital s]8[ital s] perturber inhibits autoionization by more than three powers of 10. Semiclassical quantization based on unstable periodic orbits reproduces the energies of states with equal or similar quantum numbers rather well in a standard application of the cycle-expansion technique and very well in an application using only three nonretracing periodic orbits.

• OSTI ID: 7122272
• Journal Information: Physical Review A; (United States), Journal Name: Physical Review A; (United States) Vol. 50:5; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

664100* -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
AUTOIONIZATION
BINDING ENERGY
CHARGE STATES
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY
ENERGY-LEVEL TRANSITIONS
EXCITATION
FLUIDS
GASES
HELIUM
IONIZATION
LEVEL WIDTHS
NONMETALS
PARTIAL WAVES
RARE GASES
RESONANCE
S WAVES