| 释义 |
multiplet|ˈmʌltɪplət|
[f. multiple a. and n. + -et, after doublet, triplet.]
a. A group of lines in a spectrum that are close together and spaced approximately in accordance with a simple rule; a group of related levels in an atom that differ slightly in energy, esp. a group in which this is due to differing relative orientations of either the electronic spin and orbital angular momenta, giving different values of the quantum number J (in the case of fine structure), or the electronic and nuclear angular momenta, giving different values of the quantum number F (in the case of hyperfine structure).
1922M. A. Catalán in Phil. Trans. R. Soc. A. CCXXIII. 147 As will be seen later there are many ‘groups’ of lines in the manganese spectrum with similar structure to that of the foregoing ‘group’, and for this form of regularity the name ‘multiplet’ is suggested. 1929Trans. Faraday Soc. XXV. 672 Next, the coupling between spin momenta of the electrons gave a ‘resultant’ spin vector S, which determined the multiplicity. The multiplicity was given by R = 2S + 1, if S was measured in units of h/2π. Finally, the components of a multiplet were regarded as determined by the coupling between the resultant L vector and the resultant S vector. 1942[see fine structure 1 a]. 1959Sci. News LIII. 87 In order to interpret all the observations, such as the multiplet structure of spectral lines.., it has to be assumed that the electron has, independently of its orbital motion, an intrinsic angular momentum and a magnetic moment. 1967W. R. Hindmarsh Atomic Spectra v. 50 A quantum number F can be ascribed to each hyperfine level such that the number increases by one from one level to the next and..the separation between two successive levels is..AF where A is a constant for a hyperfine multiplet. 1971A. G. Sharkey in R. I. Reed Recent Topics Mass Spectrometry 128 High-resolution mass spectrometry is unique in providing a precise mass from which a molecular formula can be derived. The basis of the high-resolution technique is the ability of the instrument to resolve multiplets, having the same nominal mass but differing in precise mass.
b. A group of sub-atomic particles that are alike as regards the values of the various quantum numbers except for the third component of isospin (and hence charge), which is different for each particle and has one of the 2I + 1 values 0, {pm}½, {pm}1,{ddd}, {pm}I (I = 0 or half-integral); also, a larger group (also called a supermultiplet) composed of a number of such charge multiplets, each likewise characterized by a different value of hypercharge (or strangeness) but having the same spin and the same parity.
In quots. 1937 more a transf. use of prec. sense.
1937Physical Rev. LI. 106 The structure of the multiplets of nuclear terms is investigated, using as a first approximation a Hamiltonian which does not involve the ordinary spin and corresponds to equal forces between all nuclear constituents, protons and neutrons. The multiplets turn out to have a rather complicated structure, instead of the S of atomic spectroscopy, one has three quantum numbers S, T, Y. Ibid. 117/1 Every one of these six states can be doubly occupied, with a particle τ = 1 and τ = -1 (neutron or proton). The half sum of the τ is denoted by Tζ and the different Tζ from -T to T united into a multiplet. 1954Proc. Nat. Acad. Sci. XL. 490 In discussing baryon states we used the intuitive argument of approximate mass degeneracy in a multiplet. 1956[see hypercharge]. 1964New Scientist 20 Feb. 458/3 The particles appear in groups, or ‘multiplets’, of particles of different charge but very nearly equal mass. 1965Ibid. 18 Mar. 738/3 Just as in the theory of SU(2) the particles are arranged in multiplets, but now they are distinguished within a multiplet by both their charge and hypercharge. The SU(3) symmetry relates not just the proton and neutron one to another, but includes also in one multiplet the six particles known as hyperons. 1970[see isospin]. 1970D. B. Lichtenberg Unitary Symmetry & Elem. Particles iii. 34 The 2I + 1 different charge states of a particle with isospin I constitute a multiplet. However, since isospin is not an exact symmetry, the different states are not exactly degenerate in energy. It is often said under such circumstances that different members of the multiplet are different particles, rather than different states of the same particle. 1973L. J. Tassie Physics Elem. Particles iv. 39 We now consider the three pions π-, π0, π+ as a charge multiplet or isospin multiplet of multiplicity 2I + 1 = 3 yielding I = 1. We identify the I3 = +1 state as the π+; I3 = 0 as the π0; I3 = -1 as the π-. Ibid. xi. 134 The arrangement of N, λ, σ and ξ into one multiplet, an octet.., is illustrated in Fig. 49.1. The mass splittings between the different isospin multiplets in the octet are about 20 times the mass splitting within isospin multiplets. |