Letter | Published:

X-Ray Spectra of Trans-Uranic Elements

Nature volume 159, page 741 (31 May 1947) | Download Citation



IN view of the recent discovery of elements with atomic numbers 93–96, it is of interest to recall a calculation based on the assumption of a minimum proper length for the world-line of an electron1. The conception that it is impossible to discriminate in space-time between two positions of the electron when the interval separating them is less than h/m0c (m0 = rest mass) leads to the result that an electron in a Bohr orbit cannot have a velocity greater than c/2. A further consequence of this is that a K-ring cannot exist in an atom for which Z> hc/22pie2and this means that the Bohr-Rutherford model would stop at Z = 96. Although the original argument leading to this result cannot be regarded as free from objection in the light of modern quantum theory, the likelihood of some such limitation remains. A more recent application of the principle of minimum length and time to the Rutherford-Bohr atom sets the upper limit to Z somewhat lower than 962.

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  1. Postmead, Portesham, Dorset.

    • J. W. FISHER
  2. Bedford College, University of London. March 6.

    • H. T. FLINT


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