Russell and Saunders

Sr (g). Vapor pressure data were reported by Ruff and Hartmann1 and Hartmann and Schneider.1 We have estimated the value for the heat of sublimation from the latter data. The values for the energy states of gaseous monatomic strontium are from Hansen and Thorsen,1 Saunders,2 Russell and Saunders,1 and Fowler.1... 

The resultant spin and orbital angular momenta are coupled, employing the method of Russel and Saunders, to give a total angular momentum characterized by the quantum number J which may assume the values ... 

When atoms have more than one valence electron, the term schemes become more complex as a coupling between the impulse and orbital momentums of the individual electrons occurs. According to Russell and Saunders (L — S) a coupling applies, where the orbital moments of all electrons have to be coupled to a total orbital momentum, as with the spin momentum. This coupling applies for elements with Z below 20, where it is accepted that the spin-orbital interactions are much lower than the spin-spin and the orbital-orbital interactions. The fact that none of the electrons in an atom can have the same set of quantum numbers is known as the Pauli rule. The total quantum number I is obtained as L = 2,1, S = Es and J = L — S,..., I + S. The term symbol accordingly becomes ... 

The two movements of the electrons are in fact not independent, they couple and the strength of the interaction usually increases with the atomic number. To simplify the treatment of this interaction, Russel and Saunders have proposed to consider this coupling at the level of the overall angular momenta and not for each individual electron. This model is valid for lighter elements and not quite adequate for lanthanides for which an intermediate coupling scheme should be applied however, it is in large use in view of its simplicity and we shall keep with it in this chapter. The Hamiltonian becomes ... 

Silva AM, Liu-Gentry J, Dickey AS et al (2005) a-Latrotoxin increases spontaneous and depolarization-evoked exocytosis from pancreatic islet P-cells. J Physiol 565 783-99 Siu R, Fladd C, Rotin D (2006) N-cadherin is an in vivo substrate for PTPo and partidpates in PTPo-mediated inhibition of axon growth. Mol Cell Biol 27 208-19 Smith DS, Russell FE (1966) Structure of the venom gland of the black widow spider Latrodectus mactans. A preliminary light and electron microscopic study. In Russell FE, Saunders PR (eds) Animal Toxins, Oxford, Pergamon, pp 1-15... 

We are now in position to derive the electronic states arising from a given electronic configuration. These states have many names spectroscopic terms (or states), term symbols, and Russell-Saunders terms, in honor of spectroscopists H. N. Russell and F. A. Saunders. Hence, the scheme we use to derive these states is called Russell-Saunders coupling. It is also simply referred to as L-S coupling. 

Russell W. Saunders School of Chemistry, University of Leeds, Leeds LS2 9JT, UK Alfonso Salz-Lopez Earth and Space Science Division, Jet Propulsion Laboratory, Pasadena, CA91109, USA... 

A second approximation neglects coupling between the spin of an electron and its orbital momentum but assumes that coupling between orbital momenta is strong and that between spin momenta relatively weak but appreciable. This represents the opposite extreme to the 77-coupling approximation. It is known as the Russell-Saunders coupling approximation and serves as a useful basis for describing most states of most atoms and is the only one we shall consider in detail. 

Figure 7.4 Russell-Saunders coupling of (a) orbital angular momenta li and I2, (b) spin angular momenta Sj and 2 and (c) total orbital and total spin angular momenta, L and S, of sip and a d electron...

Table I. g-values and Ueff of ground states In Russell-Saunders and intermediate coupling for different configurations.

Hund37 in 1926 and of oxygen and nitric oxide by Van Vleck38 in 1928 were triumphs of the theory of spectra. The magnetic moment of an atom or monatomic ion with Russell-Saunders coupling of the quantum vectors is... 

In tier (1) of the diagram (for the electronic structure of iron(III)), only the total energy of the five metal valence electrons in the potential of the nucleus is considered. Electron-electron repulsion in tier (2) yields the free-ion terms (Russel-Saunders terms) that are usually labeled by term ° symbols (The numbers given in brackets at the energy states indicate the spin- and orbital-multiplicities of these states.)... 

Finally, the magnetic moments resulting from the spin and the orbital motion interact. This spin-orbit coupling is taken into account by the total angular momentum quantum number J (Russel-Saunders coupling) ... 

In Equation 1.5, A is the spin-orbit coupling within a given Russell-Saunders multiplet, which is related to the spin-orbit coupling constant of the ion, C, by the relation A = f/2.S, the + sign applying for n <7 and the - sign for n > 7 [ 15]. The effect of spin-orbit coupling is to split the terms in multiplets with same L,... 

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