Two-Electron Excitation States in Helium.
Abstract
Resonances in the photoionization continuum of helium have been observed spectroscopically in the 165-200-A region using the synchrotron radiation from the NBS 180-MeV electron synchrotron as a background source. Twenty-one resonances have been observed,forming four series which can be associated with transitions from the ground state to two-electron excitation states of neutral helium. Two of these series converge onto the n = 2 states of He+, while the other two converge onto the n = 3 and n = 4 states of He+, respectively. The observed energies of these resonances are compared with available theoretical estimates. The absorption profile of the strongest resonance, due to the 2s2p iP state, has been studied in detail and found to be well predicted by theory.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1965
- DOI:
- 10.1086/148132
- Bibcode:
- 1965ApJ...141..364M