Measurement of the Fine Structure Separation 3 P13-3 P23 for the Helium Atom

Phys. Rev. 105, 573 – Published 15 January 1957
W. E. Lamb, Jr. and T. H. Maiman


The fine structure of helium levels (1s3p) PJ3, J=1, 2 is determined by the microwave-optical method outlined in the preceding paper. Helium atoms are excited to 3 PJ3 by electron bombardment and the optical radiation 3 PJ32 S13(3889 A) is observed with a photomultiplier tube. The intensity of this radiation changes when radio waves induce transitions between the fine structure sublevels. The separation 3 P13-3 P23 is found to be 658.0±1.0 Mc/sec, which is to be compared to the most recent optical estimates of 750±300 Mc/sec.


  • Received 1 August 1956
  • Published in the issue dated January 1957

© 1957 The American Physical Society

Authors & Affiliations

W. E. Lamb, Jr.* and T. H. Maiman

  • Stanford University, Stanford, California

  • *Present address: Clarendon Laboratory, University of Oxford, Oxford, England.
  • Present address: Hughes Research and Development Laboratories, Culver City, California.

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