Hyperfine structure

A closely spaced structure of the spectrum lines forming a multiplet component in the spectrum of an atom or molecule, or of a liquid or solid. In the emission spectrum for an atom, when a multiplet component is examined at the highest resolution, this component may be seen to be resolved, or split, into a group of spectrum lines which are extremely close together. This hyperfine structure may be due to a nuclear isotope effect, to effects related to nuclear spin, or to both. See Isotope shift, Spin (quantum mechanics)

The measurement of a hyperfine structure spectrum for a gaseous atomic or molecular system can lead to information about the nuclear magnetic and quadrupole moments, and about the atomic or molecular electron configuration. Important methods for the measurement of hyperfine structure for gaseous systems may employ an interferometer, or use atomic beams, electron spin resonance, or nuclear spin resonance.

hyperfine structure

[′hī·pər‚fīn ′strək·chər]

(spectroscopy)

A splitting of spectral lines due to the spin of the atomic nucleus or to the occurrence of a mixture of isotopes in the element. Abbreviated hfs.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Hyperfine Structure

the splitting of atomic energy levels into closely spaced sublevels as a result of the interaction of the nuclear magnetic moment with the magnetic field of the atomic electrons. The energy δE of this interaction depends on the possible relative orientations of the nuclear spin and the electron spins. The number of these orientations determines the number of components of the hyperfine structure. Energy levels can also be split and shifted as a result of the interaction of the nuclear quadrupole moment with the electric field of the electrons.

The spacing between fine structure sublevels is 1,000 times greater than the spacing between hyperfine structure sublevels, since the energy of the spin-orbit interaction is 1,000 times greater than δE. Because of the hyperfine splitting of levels, an atomic spectrum exhibits instead of a single spectral line a group of closely spaced lines called the hyperfine structure in the spectral line.

The hyperfine structure in a spectral line can be complicated by isotope shifts—that is, by differences in the frequencies of the spectral lines of the isotopes of an element. In this case, there occurs a superposition of the spectra of the various isotopes of the element. For heavy elements, isotope shifts are of the same order of magnitude as δE.

Hyperfine structure can also be observed in the spectra of molecules and crystals.

REFERENCES

Shpol’skii, E. V. Atomnaia fizika, 6th ed., vol. I. Moscow, 1974.
Frish, S. E. Oplicheskie spektry atomov. Moscow-Leningrad, 1963.
Frish, S. E. Speklroskopicheskoe opredelenie iadernykh momentov. Leningrad-Moscow, 1948.

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References in periodicals archive

(1950) The influence of nuclear structure on the hyperfine structure of heavy elements.

This clearly shows that Nagaoka was determined to devote himself to optical spectroscopy in order to analyze the complexity of the atomic spectra, which was later known as fine structures due to the electron spin-orbit coupling and hyperfine structures caused by the nuclear spin and shape.

From the Ruark and Schuler-Jones papers it is clear that the Nagaoka-Sugiura-Mishima work had become internationally well accepted as excellent data on hyperfine structures. Regrettably, however, it seems that no Japanese physicists were aware of this fact.

Nagaoka's atomic model and hyperfine interactions

Lovas and co-workers identified cyanoallene toward the TMC-1 molecular cloud aided by its hyperfine structure (168).

(Letters) 455, L201 (1995), Microwave Spectra, Hyperfine Structure, and Electric Dipole Moments for Conformers I and II of Glycine.

Evolution of microwave spectroscopy at the National Bureau of Standards (NBS) and the National Institute of Standards and Technology (NIST)

These calculations reflect the qualitative features of the energy spectrum of antiferromagnetic particles given in Section 2 and their manifestation in absorption spectra [18,22], namely, the transition from the well-resolved magnetic hyperfine structure at low temperatures to the higher-temperature single line against the background of the magnetic hyperfine structure with sharply asymmetric lines at intermediate temperatures.

As long as in most cases the experimental Moossbauer spectra of magnetic nanoparticles display the high-temperature collapse of the magnetic hyperfine structure into a quadrupolar doublet of lines [9-13, 23], but not into a single line, one should perform generalization of a formalism described in the previous section on the presence of the hyperfine quadrupolar interaction.

These spectra demonstrate both the specific shapes of the hyperfine magnetic structure, reflecting qualitative features of the energy spectrum of antiferromagnetic particles, described in the previous section, and the transition from the well-resolved magnetic hyperfine structure at low temperatures to the higher-temperature quadrupolar doublet of lines, which is usually observed in the experiments [913, 23].

Excitation Spectrum of the Neel Ensemble of Antiferromagnetic Nanoparticles as Revealed in Mossbauer Spectroscopy

Hama, "Relation between Ge(2) center and 11.9 mT hyperfine structure of ESR spectra in Ge-doped silica fibers," Japanese Journal of Applied Physics, vol.

A minireview of the natures of radiation-induced point defects in pure and doped silica glasses and their visible/near-IR absorption bands, with emphasis on self-trapped holes and how they can be controlled

where [gamma]T is the electronic specific heat, [[beta].sub.3][T.sup.3] + [[beta].sub.5][T.sup.5] is the phonon specific heat, [delta][T.sup.n] is the spin wave specific heat (n = 3/2 for ferromagnetic spin wave; n = 2 for anti-ferromagnetic spin wave), and [alpha]/[T.sup.2] is the specific heat of the hyperfine structure [4].

The low temperature specific heat of [Pr.sub.0.65][Ca.sub.0.35]Mn[O.sub.3]

For v = 0 we expect the unresolved hyperfine structure to broaden the line by [approximately equal to] 2 MHz.

(21) but generalized here to include hyperfine structure. The molecular Rabi matrix elements depend on the excited rovibrational-hyperfine state quantum numbers, F'p'[beta]vJ', and the ground state hyperfine levels [f.sub.a] and [f.sub.b] of the two colliding atoms.

A spectroscopic determination of scattering lengths for sodium atom collisions