Zeeman effect

Physics, Optics.

the dividing of a spectral line or lines as a result of placing a radiation source in a magnetic field. The division consists of three equally spaced lines (normal Zeeman effect) in systems for which the spin quantum number is zero, or of three or more unequally spaced lines (anomalous Zeeman effect) in systems for which the spin quantum number is not zero. Also called Zeeman splitting. Cf. Paschen-Back effect.

[1895-1900; named after P. ZEEMAN]

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Splitting of a spectral line (see spectrum) into two or more lines of different frequencies.

The effect occurs when the light source is placed in a magnetic field. It has helped identify the energy levels in atoms; it also provides a means of studying atomic nuclei and electron paramagnetic resonance (see magnetic resonance) and is used in measuring the magnetic field of the Sun and other stars. It was discovered in 1896 by Pieter Zeeman (1865–1943); he shared the second Nobel Prize for Physics (1902) with Hendrik Antoon Lorentz, who had hypothesized that a magnetic field would affect the frequency of the light emitted.

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▪ physics

      in physics and astronomy, the splitting of a spectral line into two or more components of slightly different frequency when the light source is placed in a magnetic field. It was first observed in 1896 by the Dutch physicist Pieter Zeeman (Zeeman, Pieter) as a broadening of the yellow D-lines of sodium in a flame held between strong magnetic poles. Later the broadening was found to be a distinct splitting of spectral lines into as many as 15 components.

      Zeeman's discovery earned him the 1902 Nobel Prize for Physics, which he shared with a former teacher, Hendrik Antoon Lorentz, (Lorentz, Hendrik Antoon) another Dutch physicist. Lorentz, who had earlier developed a theory concerning the effect of magnetism on light, hypothesized that the oscillations of electrons inside an atom produce light and that a magnetic field would affect the oscillations and thereby the frequency of the light emitted. This theory was confirmed by Zeeman's research and later modified by quantum mechanics, according to which spectral lines of light are emitted when electrons change from one discrete energy (energy state) level to another. Each of the levels, characterized by an angular momentum (quantity related to mass and spin), is split in a magnetic field into substates of equal energy. These substates of energy are revealed by the resulting patterns of spectral line components.

      The Zeeman effect has helped physicists determine the energy levels in atoms and identify them in terms of angular momenta. It also provides an effective means of studying atomic nuclei and such phenomena as electron paramagnetic resonance. In astronomy, the Zeeman effect is used in measuring the magnetic field of the Sun and of other stars. See also Stark effect.

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