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History of the Taylor-Phipps version of the Stern-Gerlach experiment

  1. Nov 20, 2009 #1

    I'm at the tail end of writing an essay about the Stern-Gerlach experiment and I am wondering if anyone knows of any reliable sources that discuss the historical context of the Taylor-Phipps version of the Stern-Gerlach experiment using hydrogen.

    All of the sources that I find use the Schrodinger equation to claim that no splitting would be expected without spin, how do they know that the Schrodinger equation was accepted as right? Were there other compelling experiments to suggest that the Schrodinger equation must be real? They make it seem like the Bohr-Sommerfeld theory had been discarded already despite it being consistent with experiment and they don't mention why.

    I have the original paper and they confirm the value of the Bohr magneton and that's it.

    Any help would be greatly appreciated.
  2. jcsd
  3. Nov 21, 2009 #2
    In the Schrodinger-equation based theory, the S-state electron with no spin would have no magnetic moment. So in the Stern-Gerlach(S-G) experiment, no splitting would be seen in that state.

    In the Bohr-Sommerfeld model, due to the quantization of the angular momentum (+1,0,-1), it is said to be splitted into three in the S-G experiment.
    But in page 438 of the Historical Development of Quantum Theory by Jagdish Mehra, which is a good textbook of the S-G and Bohr model history,

    Niels Bohr had excluded the possibility that the spacial quantum number n1 be zero because then the plane of the electron orbit would contain the direction of magnetic field and the electron motion might become instable under certain conditions. Terefore in quantum theory(of Bohr model), the magnetic moment of an atom should possess only two discrete positions, parallel or antiparallel.

    Bohr commented this thinking that also in Bohr model, S-G experiment would show the two splitting.
    I think his idea at this time is very natural.

    The magnetic moment= g-factor x angular momentum.
    So the S-state electron of the Bohr model has the same magnetic moment as that of the Schrodinger equation model (due to 1 x 1 = 2 x 1/2(spin) = Bohr magneton).
    (I was looking for, but the hydrogen S-G experiment was not found in the upper book. Sorry.)

    The Schrodinger equation was left as the result of the long struggle for the proper model which shows the correct helium ground state energy in 1920's.
    See this thread for more. (#19 by ytuab)

    And the anomalous Zeeman effect was also important, which is a little complicated.
  4. Nov 21, 2009 #3
    Thank you,

    The fact that the Schrodinger equation could explain the helium energy and the Bohr-Sommerfeld model could not is exactly what I was missing.
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