[fahyn] 
| a group of lines that are observed in the spectra of certain elements, as hydrogen, and that are caused by various couplings of the azimuthal quantum number and the angular momentum quantum number. |
[uhl-truh-struhk-cher] | the structures of a cell that are revealed by electron microscopy. |
| fine structure (fīn) n.
|
| ul·tra·struc·ture (ŭl'trə-strŭk'chər) n. The detailed structure of a biological specimen, such as a cell, tissue, or organ, that can be observed only by electron microscopy. Also called fine structure. |
fine structure
in spectroscopy, the splitting of the main spectral lines of an atom into two or more components, each representing a slightly different wavelength. Fine structure is produced when an atom emits light in making the transition from one energy state to another. The split lines, which are called the fine structure of the main lines, arise from the interaction of the orbital motion of an electron with the quantum mechanical "spin" of that electron. An electron can be thought of as an electrically charged spinning top, and hence it behaves as a tiny bar magnet. The spinning electron interacts with the magnetic field produced by the electron's rotation about the atomic nucleus to generate the fine structure.
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