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单词 fine structure
释义
fine structure

Physics
  • Closely spaced optical spectral lines arising from transitions between energy levels that are split by the electron spin. They are visible only at high resolution. Hyperfine structure, visible only at very high resolution, results from the influence of the atomic nucleus on the allowed energy levels of the atom.


Astronomy
  • Closely spaced spectral lines from a given element. Fine structure has two causes. One is the interaction of electrons in an atom with the magnetic field of the atom itself, and the second is relativistic effects on the electrons’ kinetic energies due to their orbital motion. These combined effects create a fine splitting of the various principal energy levels and produce several closely spaced lines instead of one. For hydrogen the fine structure is so fine (0.006 nm) that it is unobservable in stars. However, more complex atoms such as sodium can have more discernible fine structure because of the presence of many other electrons in the atom. The sodium D lines are an easily observable example of fine structure, with a separation of 0.6 nm. Hyperfine structure is on a still smaller scale.


Chemistry
  • Closely spaced spectral lines arising from transitions between energy levels that are split by the vibrational or rotational motion of a molecule or by electron spin. They are visible only at high resolution. Hyperfine structure, visible only at very high resolution, results from the influence of the atomic nucleus on the allowed energy levels of the atom.


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