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Il Nuovo Cimento D

, Volume 2, Issue 3, pp 801–829 | Cite as

Two-photon transitions between discretenS states in atomic He

  • D. Ricca
  • F. Bassani
Article

Summary

The two-photon transition probabilities from the ground state 11 S and from the metastable states 21 S and 23 S to the lowest excited states are computed in He. A configuration interaction approach is used, and a detailed comparison between the «length» and the «velocity» gauges leads to an estimate of 1% accuracy. Correlation effects are found to account for about 20% of the transition probabilities. The life-time of the 21 S state is ≅19.6 ms. The two-photon transition probabilities display a dramatic dependence on frequency, characterized by resonances and transparencies.

PACS. 32.80

Atomic photon processes 

Riassunto

Si calcolano le probabilità di transizione a due fotoni nell’elio atomico dallo stato fondamentale 11 S e dagli stati metastabili 21 S e 23 S agli stati eccitati di piú bassa energia (n≤4). Si usa il metodo dell’interazione di configurazioni, che dà un’accuratezza dell’1%, stimata dal confronto tra la «gauge di lunghezza» e «la gauge di velocità». Effetti di correlazione contribuiscono circa 20% alle probabilità di transizione. La vita media dello stato 21 S è di circa 19.6 ms. Le probabilità di transizione a due fotoni mostrano una forte dipendenza dalla frequenza, caratterizzata da risonanze e da trasparenze.

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Copyright information

© Società Italiana di Fisica 1983

Authors and Affiliations

  • D. Ricca
    • 1
  • F. Bassani
    • 1
  1. 1.Scuola Normale SuperiorePisaItalia

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