Static coupling

The quadrupolar quasi-static coupling in NF3 — 7.068 MHz— is very close to the value obtained from microwave measurements — 7.07 MHz — this feature may be interpreted as a clue that intermolecular effects are negligible in this compound unless, by a fortuitous coincidence, thes intermolecular effects are cancelled by some other mechanism, such as a molecular deformation in the solid (the coupling is very sensitive to slight variations of the pyramidal angle, as discussed below). 

The difference between the quasi-static coupling for ammonia in the solid state — 3.47 MHz - and that measured in the gas by microwave spectroscopy — 4.08 MHz — cannot be explained by the contribution of the crystalline electric field gradient alone, but must be attributed to a redistribution of the bonding electrons in the molecule under the influence of the crystalline electric field or of the intermolecular hydrogen bonds. 

A certain electronic transition in a polyatomic system can be equally described either within the adiabatic or within the diabatic basis set as the transitions can be induced either by the dynamic or by the static coupling,... 

According to Ekj. (7), it is the dielectric dynamics of the homogeneous solvent, as expressed in C (fc, ), that is the source of the time dependence of the estimate Z t) of the solvation tcf. In the RDT approximation the effect of the solute-solvent interactions is carried by the static coupling function B (fc). This factorization (to a function of the homogeneous solvent dynamics times a function of the static solute-solvent structure) is a characteristic feature of the RDT theory. The renonnalized character of the coupling function allows us to bypass the two-time many-point correlation functions that would necessarily appear in a dynamical theory that explicitly addressed the inhomogeneity of the solvent in the neighborhood of the solute particle. 

Further he shows that the dynamic-coupling term runs more or less parallel with the static coupling term. The dynamic term becomes more important if the covalency increases. Under certain conditions both terms are of comparable magnitude. We will present the final result below. 

In the static coupling scheme, J Q) of Eq. 10 causes transitions of an electron from the donor to the acceptor. It works most effectively around Q = Qc, where diabatic... 

Static coupling between the transition dipoles of the donor and the acceptor is a long-range interaction, which falls off relatively slowly with distance (Figure 1). 

To further investigate the role of motion in triplet energy transfer, three carotenoporphyrins, 32,33, and 34, were synthesized [73]. In these molecules, the static coupling along the linkage bonds was nearly constant and relatively weak, but the constraints on intramolecular motion differed considerably. From detailed NMR studies in solution the time average conformations were determined. The para-linked isomer (32) was found to be roughly linear, the meta-linked one (33) approximately L shaped, and the ortho-linked one (34) partially folded. 

The states of symmetry A2 have a simple feature the condition that the wave function become negative under reflection in the plane x = y rules out all orbitals on the oxygen atom numbered 3 and therefore all coupling between orbitals of different phases. The solutions become independent of k. We consider the orbitals in a particular plane of constant 2, as shown in Fig, 19-6. Symmetry requires that the coefficients on the Sj) and. 2> states be equal and opposite. The same is true of the pi>and pj) states (not shown in Fig. 19-6). Thus we have an si 2) static coupled with a d state an an uncoupled pi 2) band, both of symmetry A2, and we obtain final energies... 

Cobalt(ni).—The optical activity associated with d-d transitions in dissymmetric cobalt(iii) complexes has been examined in terms of a model which incorporates both ligand field theory and the one-electron static-coupling theory of optical activity. Expressions have been obtained which relate the sign of the net or total d-d rotatory strength to specific stereochemical features in the ligand environment. Sector rules based on these expressions have been proposed and tested. A model for predicting the photo-reactions and quantum yields of cobalt(iii) complexes has been devised. ... 

There is a second type of chiral quadruple-bonded species in which the twist is zero or close to zero. " In these cases the M02 unit must be treated as an achiral chromophore and the CD (which is weak) can be explained by one electron static coupling. This theory has also been used to explain the CD of singly bonded Rh2(5 -mandelate)4 (EtOH)2. ... 

Motions much faster than the static coupling result in isotopic frequency spectra, such as the C chemical shift spectrum of l,2-dilauroyl-yn-glycero-3-phosphochoIine (DLPC) obtained using MAS shown in Figure 6.87 (Leftin and Brown 2011). 

Ifast di Cfast diff, which in fact enables us, on the dynamic level, to demonstrate the strong correlation between the diffusion in the two zones A and B of the electrode in question. The static coupling is expressed by relation [2.30], which links the limit currents. 

Figure 4.5 Cross-polarised 75 MHz C spectra of solid poly(methyl methacrylate) A, static, coupled B, static, proton-decoupled C, with MAS, coupled D, with MAS, proton-decoupled...

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