Multiplet site

Figure 20.1. Schematics of reactant (R) to product (P) reaction on multiplet sites in a < 100 nm-thick crystal of an early transition metal oxide. Re-oxidation of the catalyst surface after desorption of P, by diffusion from bulk or after reduction of dioxygen O2 to 0. ...

A multiplet centered at 8 4.90 was assigned to the C-16 proton, which exhibited COSY interactions with the C-15 methylene and C-17 methine protons. Since an acetoxy group was inferred from IR absorptions and the presence of a singlet at 8 1.90 in the ID H-NMR spectrum, C-16 seemed to be a plausible site of its substitudon in ring D of the skeleton (fragment III). 

Fig. 7.12 Cu( Ni) emission Mosshauer spectra of (a) YBa2Cu307 and (b) YBa2Cu30s. Two quadrupole multiplets corresponding to at the Cu(l) and Cu(2) sites are shown in spectrum (a). The Zeeman multiplet from the Cu(2) sites and the singlet from the Cu(l) sites are shown in spectrum (b) (from [26])...

Inspection of Equation 1.23 and consideration of the properties of 3-y and 6-j symbols confirm that only even A--values contribute to crystal field splitting. Further, it indicates that mixing between levels belonging to different / multiplets can only occur if terms with k site symmetry of the lanthanide, in much the same way as discussed above for the Stevens formalism. 

Although the 13C NMR provides quantitative information on the chlorination at the methyl site, it is less definitive for the backbone carbons. The multiplet centered at 44.3 ppm attributed to the methylene carbon in the main chain decreases at high chlorine contents as does the a-carbon peak. At the same time a close examination of the 13C NMR reveals the appearance of broad weak signals at about 54 and 68 ppm. These peaks may be due to chlorine substitution of the protons on the polymer main chain but this assignment is not definitive since the shift in peak position relative to the unchlorinated carbon is not as great as it would be expected for chlorine substitution. 

A Ce3+ ion has the configuration 4fl so that its ground state is the Russell-Saunders multiplet 4F. In a crystal of CaF2 containing dissolved CeF3, the Ce3+ ions substitute for Ca2+ ions at lattice sites so that each Ce3+ ion is at the center of a cube of F ions (see Exercise 7.4-1). This cubic field is of a strength intermediate between the... 

The splitting of free-ion levels by the action of a crystal field depends on the symmetry of the crystal field which in turn reflects the symmetry of the arrangement of the neighboring ions. This property can thus be used to get evidence about the point group symmetry of a site in a given solid once the splitting of the free-ion multiplets have been determined (see, for example, sect. 5.8 of Gorller-Walrand and Binnemans (1996)). This can be a very useful... 

In catalysis, one of the key concepts to understand catalytic action is the so-called active sites [28], The essential concept behind this term is the fact that catalytic activity in solids is restricted to specific sites in the catalyst surface. Another factor influencing catalytic activity is the geometric factor, that is, a properly spaced array of atoms on the solid surface, named Balandin multiplets,... 

In general, when the site spinor xpvp is not symmetric with respect to any indices, the possible states of two quartets of spins s = 1/2 consist of 70 multiplets. A wave function represented by a sixth-rank spinor contains only 20 of them. Accordingly, the cell Hamiltonians H12 and 3 can be represented by the sum of projectors onto the 50 missing multiplets ... 

When the site spinor vj/V - p is a symmetric fourth-rank spinor QA u/p (corresponding to the two-dimensional AKLT model[13]), only the quintet component out of the six multiplets on each spin quartet is present in the wave function (60). The sixth-rank spinors (62) are symmetric with respect to two triplets of indices and, hence, contain four multiplets with S = 0, 1, 2, 3 formed from two quintets. Consequently, the cell Hamiltonian (Hi and H coincide in this case) has the form... 

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