The Zeeman Effect and the Stark Effect

2002 ◽  
pp. 257-267
Author(s):  
Franz Schwabl
Keyword(s):  

Author(s):  
Anthony Duncan ◽  
Michel Janssen

This is the first of two volumes on the genesis of quantum mechanics. It covers the key developments in the period 1900–1923 that provided the scaffold on which the arch of modern quantum mechanics was built in the period 1923–1927 (covered in the second volume). After tracing the early contributions by Planck, Einstein, and Bohr to the theories of black‐body radiation, specific heats, and spectroscopy, all showing the need for drastic changes to the physics of their day, the book tackles the efforts by Sommerfeld and others to provide a new theory, now known as the old quantum theory. After some striking initial successes (explaining the fine structure of hydrogen, X‐ray spectra, and the Stark effect), the old quantum theory ran into serious difficulties (failing to provide consistent models for helium and the Zeeman effect) and eventually gave way to matrix and wave mechanics. Constructing Quantum Mechanics is based on the best and latest scholarship in the field, to which the authors have made significant contributions themselves. It breaks new ground, especially in its treatment of the work of Sommerfeld and his associates, but also offers new perspectives on classic papers by Planck, Einstein, and Bohr. Throughout the book, the authors provide detailed reconstructions (at the level of an upper‐level undergraduate physics course) of the cental arguments and derivations of the physicists involved. All in all, Constructing Quantum Mechanics promises to take the place of older books as the standard source on the genesis of quantum mechanics.



While the Stark-effect has not been studied so extensively as the Zeeman-effect, either in the experiments or in their interpretations, many of the more prominent features have been observed and have received adequate explanation on the quantum theory. Among these may be mentioned the patterns characteristic of the different series in the singlet system of parhelium. The variety of observed patterns in the Stark-effect, as contrasted with the normal Zeeman-effect found for all series of this system, arises from a differential action of the external electric field on the initial and final states, and a breaking down of the usual selection rule for the azimuthal quantum number. Some simplification is brought about, however, by the fact that only the absolute value of the quantum number m has any meaning in the interpretation of these photographs, since the action of the field is the same for right or left-handed motion of the outer electron in its orbit. This results in asymmetrical patterns for all the lines. The number of components observed in the patterns of individual lines of parhelium is in accord with the theoretical view that the vector j (here equal to l ) is resolved along the direction of the applied field to give the integral m values ranging from - j to + j , and that the usual selection rule holds for m . The displacements and intensities are in excellent agreement with the theoretical calculations based on the perturbation theory of quantum mechanics. The spacing of the sub-levels identified by ± m in the initial state is decidedly irregular in the Stark-effect as compared with the normal Zeeman-effect, where the displacements are proportional to m . The Zeeman order of the levels is usually reversed, in fact, and the spacing is uneven. Displacements in the final state are theoretically very small, and have not been observed with certainty. In the Stark-effect for orthohelium (triplet system) the same group of patterns was observed. An explanation of these observations, which is slightly less satisfactory than that obtained with parhelium, has been made by similar methods, neglecting the electron spin. Thus the m values were again given ranges determined in each case by the l of the outer electron, and not by the j for the whole atom. Most of the plates failed to reveal any of the fine structure of the normal orthohelium spectrum.





1975 ◽  
Vol 30 (10) ◽  
pp. 1265-1270 ◽  
Author(s):  
L. Engelbrecht ◽  
D.H. Sutter

Abstract It is pointed out that the translational Lorentz effect which has been neglected in all previous analysis of rotational Zeeman spectra has considerable effects on the overall appearance of the Zeeman multiplets if the rotational transitions show first order Stark effect. This situation occurs for symmetric tops and for E-species transitions of molecules with low barrier internal rotations. Inclusion of the translational Lorentz effect leads to corrections to the published g‖-values of symmetric tops which are far outside the quoted experimental uncertainties. As an example numerical results are given for CH3F and CH3CCH.



1. Indications of the occurrence of fractional quantum numbers have already been found by Kratzer from a study of certain band spectra, and by Curtis in his experimental investigation of helium bands. Heisenberg has also employed half-integral numbers in a quantum theory of the anomalous Zeeman effect with considerable success. The fourth of the slightly extended quantum conditions recently suggested by W. Wilson and applied by the present writer to the Zeeman effect involves a fractional quantum number, as O. W. Richardson has pointed out. K. F. Niessen, in his work on the positively ionised hydrogen molecule, observes certain discontinuities in the energy graphs between symmetrical and asymmetrical models which strongly the occurrence of half-integral quantum orbits for the latter. He refrains, however, from making this assumption, on the ground that it would necessitate the adoption of half numbers in the somewhat allied case of the Stark effect.



1995 ◽  
pp. 257-267
Author(s):  
Franz Schwabl
Keyword(s):  


1972 ◽  
Vol 27 (1) ◽  
pp. 77-91 ◽  
Author(s):  
R. Ley ◽  
W. Schauer

AbstractHyperfine structure, Stark effect and Zeeman effect of the TlCl molecule have been measured with a molecular beam apparatus using electric four poles as deflecting fields and a homogeneous electric field parallel to a superimposed magnetic field in the transition region. Electric dipole transitions were induced between the hyperfine structure levels of the first rotational state J = 1 in both strong and weak external field.The following quantities could be evaluated from the spectra: the electric dipole moment µel and the magnetic rotational dipole moment µJ of the molecule, the nuclear spin-rotational interactions c1 and c2, the scalar and tensor part of the nuclear dipole-dipole interaction dS and dT, the quadrupole coupling constant e q Q of the Cl nucleus, the anisotropy of the magnetic susceptibility ξ⊥− ξ∥ , the anisotropy of the magnetic shielding of the external magnetic field at the position of both nuclei (σ⊥- σ∥)1 and (σ⊥- σ∥)2, the magnetic moment of the Cl nucleus multiplied by the scalar part of the magnetic shielding tensor µ2 · (1 - σS)2. For the most abundant isotop 205Tl35Cl the vibrational dependence of most of these quantities was measured in the vibrational states v =0, 1, 2, 3. Isotopic effects for 203Tl35Cl, 205Tl37Cl and 203Tl37Cl were investigated in the ground vibrational state. In addition the vibrational dependence of the electric dipole moment was measured for all isotopic species.It is pointed out that the usual connections between (σ⊥- σ∥)1,2 and c1,2 and between ξ⊥− ξ∥ and µJ do not hold when the excited electronic states of the molecule obey Hund’s coupling case c, which occurs most probably in TlCl.



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