Fine Structure

Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to Fine Structure: hyperfine structure

Fine structure (spectral lines)

The closely spaced groups of lines observed in the spectra of the lightest elements, notably hydrogen and helium. The components of any one such group are characterized by identical values of the principal quantum number n, but different values of the azimuthal quantum number l and the angular momentum quantum number j.

In atoms having several electrons, this fine structure becomes the multiplet structure resulting from spin-orbit coupling. This gives splittings of the terms and the spectral lines that are “fine’’ for the lightest elements but that are very large, of the order of an electronvolt, for the heavy elements.

Fine Structure


(or multiplet splitting), a splitting of the energy levels and spectral lines of atoms, molecules, and crystals that is caused by spin-orbit coupling. The number of sublevels into which an energy level is split depends on the number of possible spin orientations—that is, on the multiplicity K—and does not exceed K. In particular, for alkali-metal atoms the spin of the outer electron can have two orientations (K = 2); in this case, the energy levels are split into two sublevéis (doublet splitting), and the spectral lines are split into two closely spaced levels (doublets). For light atoms the magnitude of the fine-structure splitting of energy levels does not exceed 10–4 electron volt; for spectral lines the corresponding magnitude is several wave number units (cm–1). The splitting increases markedly as the nuclear charge Z becomes larger. The splitting of the energy levels of heavy atoms may reach several tenths of an electron volt.


fine structure

[¦fīn ′strək·chər]
(atomic physics)
The splitting of spectral lines in atomic and molecular spectra caused by the spin angular momentum of the electrons and the coupling of the spin to the orbital angular momentum.
References in periodicals archive ?
The other had the same spectrum of [alpha]-carotene and presented more defined spectral fine structure compared to that of [beta]-carotene; it may be identified as zeinoxanthin or [alpha]-cryptoxanthin.
The present paper describes the fine structure of hagfish spermiogenesis in detail, using the Japanese hagfish Eptatretus burgeri.
Unfortunately, no other investigations dealing with fine structure of theridiid spermatozoa exist to allow an evaluation of our results.
The fine structure of these scales, independent of their tooth pattern, showed a top surface with a lattice of parallel longitudinal ridges.
The new fine structure would be $250 for a first offense, $500 for a second and $1,000 for subsequent offense.
Strong capabilities have been built in capillary and nanoscale LC separations and in the use of MS for the identification and fine structure characterization of protein samples digested by enzymes.
1998) studied the fine structure of the tongue of penguin which presented the dorsal surface densely distributed with large spine-like lingual papillae.
As a result, Clean Water Act violators who would have been fined $27,500 under the old fine structure will now have to pay $31,500.
Under the proposed fine structure, Arsenal players would end up paying more than pounds 250,000 in penalties next season if they maintained their discipline rate for this season.