Contribution dipolar

Here the ijk coordinate system represents the laboratory reference frame the primed coordinate system i j k corresponds to coordinates in the molecular system. The quantities Tj, are the matrices describing the coordinate transfomiation between the molecular and laboratory systems. In this relationship, we have neglected local-field effects and expressed the in a fomi equivalent to simnning the molecular response over all the molecules in a unit surface area (with surface density N. (For simplicity, we have omitted any contribution to not attributable to the dipolar response of the molecules. In many cases, however, it is important to measure and account for the background nonlinear response not arising from the dipolar contributions from the molecules of interest.) In equation B 1.5.44, we allow for a distribution of molecular orientations and have denoted by () the corresponding ensemble average ... 

Wlien is very short, which is almost always true with nuclei having/> 1/2, the dipolar contribution to relaxation will be negligible and, hence, there will be no contributions to the integral from either NOE or saturation. However, resonances more than about 1 kHz wide may lose intensify simply because part of the FID will be lost before it can be digitized, and resonances more than 10 kHz wide may be lost altogether. It is also hard to correct for minor baseline distortions when the peaks themselves are very broad. 

Because the five-membered ring is a substituted cyclopentadienide anion in some dipolar resonance stmctures, it might be expected that exocyclic groups that could strongly stabilize a positive charge would lead to a larger contribution from dipolar stmctures and enhanced stability. The stmctures 13 and 14 are cases in which a dipolar contribution would be feasible. 

Equation (5) shows that the electric potential drop consists only of dipolar contributions. The corresponding electrode potential is what is termed the... 

Since a metal is immersed in a solution of an inactive electrolyte and no charge transfer across the interface is possible, the only phenomena occurring are the reorientation of solvent molecules at the metal surface and the redistribution of surface metal electrons.6,7 The potential drop thus consists only of dipolar contributions, so that Eq. (5) applies. Therefore the potential of zero charge is directly established at such an interface.3,8-10 Experimentally, difficulties may arise because of impurities and local microreactions,9 but this is irrelevant from the ideal point of view. 

This simple theoryis based on the expectation that, to a reasonable degree of approximation, proton-proton, dipolar contributions to the measured spin-lattice relaxation-rate are pairwise additive and decrease as a simple sixth power of the interproton distance. The simplified version of the dipole-dipole mechanism is summarized in the following two equations for spin i coupled intramolecularly with a group of spins j... 

Tjandra, N., Bax, A. Measurement of dipolar contributions to /ch splittings from magnetic-field dependence of J modulation in two-dimensional NMR spectra./. Magn. Reson. 1997, 124, 512-515. 

An anisotropic spin-dipolar contribution B arising from nonspherical distribution of the electronic spin density. 

Since the core polarization will give a negative spin density at the iron nucleus, it is expected that in the state the isotropic and dipolar contributions partially cancel each other along the Fe-O bond direction while they will reinforce each other along this direction in the state. 

Each of the eight hyperfine resonances is an unresolved quadmpole doublet, due to the quadmpole interaction of Os in the hexagonal Os metal source. The authors have interpreted the hyperfine fields in terms of core polarization, orbital and spin-dipolar contributions. 

The dipolar contributions to the local field diverges if the terms are replaced by their absolute values. 

The general form of the dipolar contribution to the hyperfine term of the Hamiltonian is ... 

The difference between the fine structure parameters computed from the experimental g-tensor and those measured from the spectrum are presumed to be the electron dipolar contributions. 

Fohlisch99 reported a remarkable dependence of the electron spectra of quino-cyclopropenes on their structure. As shown in Table 9, the merocyanine-like quino-cyclopropenes show positive solvatochromy when they contain an anthraquinonoid chromophore (198), but negative solvatochromy when they contain a benzoquino-noid system (199). This can be interpreted in terms of a markedly increased participation of dipolar resonance forms in the ground state of the benzoquinonoid 199 compared to the anthraquinonoid 198. From the dipole moment of 198 (9.4 D99 ) the dipolar contribution was estimated to be in the range of 23%. 

Computer simulation of the experimental spectra in the frozen solution points to a spin-localized structure independent of the temperature. This interpretation is unambiguous because, in the solid state, the dipolar contributions of the hyperfine interaction A(dip) for all three principal... 

This apparent anomaly may be due to increased dipolar contributions as well as to possible decrease in the free volume of polymer. Free volumes of the resin... 

One of the possibilities is to replace the evolution of the single-quantum states by the multiple-quantum ones during extended evolution periods. As theoretically predicted by Griffey and Redfield [34] and experimentally demonstrated by Grzesiek and Bax [35], keeping a spin pair in the state of multiple-quantum coherence (MQ) eliminates most of the dipolar contribution to the spin-spin relaxation. With the X-H (X is a heteronucleus) spin pairs, this is partially offset by a higher rate of proton cross-relaxation in the transverse plane with the remote H spins. Since the MQ coherences consist of transverse... 

By measuring the enhanced relaxation in enriched water, it is possible to obtain the dipolar contribution to proton relaxation... 

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