Ionization Energies and Quantum Electrodynamic Effects in the Lower 1 sns and 1 snp Levels of Neutral Helium (4HeI)

Published

July 1, 1998

Author(s)

B Drake, William C. Martin

Abstract

Ionization energies for several of the lower lying S- and P-states of helium are deduced from a combination of theory and a variety of high precision measurements of transition energies. High precision variational methods are reviewed and used to subtract the nonrelativistic energy and lowest order α² relativistic corrections from the ionization energies. The remaining quantum electrodynamic (QED) shift of order α^3^ and higher is calculated in an extended Kabir-Salpeter formalism and compared with experiment. The comparison verifies the usefulness of the Kabir-Salpeter formalism for terms at least up to order α⁴, and it verifies and asymptotic 1/n³ scaling law for the two-electron corrections to the Bethe logarithm. The asymptotic scaling law is used to obtain improved semi-empirical estimates for the ionization energies of the higher-lying 1sns ¹S and ³S states up to n = 10. A revised comprehensive listing is given for the ionization energies of all states of helium up to n = 10 and angular momentum L=7, together with quantum defect extrapolations for the S-states.

Citation

Canadian Journal of Physics

Volume

76

Pub Type

Journals

Keywords

atomic energy levels, atomic spectroscopy, atomic theory, helium, ionization energies, QED

Citation

Drake, B. and Martin, W. (1998), Ionization Energies and Quantum Electrodynamic Effects in the Lower 1 sns and 1 snp Levels of Neutral Helium (4HeI), Canadian Journal of Physics (Accessed June 15, 2025)