Magnetic dipolar interaction

Hd describes the direct magnetic dipolar interactions that occur through-space between a spin-pair. This interaction is also anisotropic and the strength of this perturbation is given in Hz by where 7 71, is the product of the... 

Magnetic dipolar interactions can be removed by the application of a high power decoupling field at the resonance frequency. 

A magnetic dipolar interaction between the electronic and nuclear spins is given by... 

In solids, the averaging due to fast movement will not occur, or even if it does, occurs partially then, the effects of direct dipolar couplings can be observed [72,73], The direct magnetic dipolar interaction between nuclear spins causes a nucleus with spin projection, ml5 to produce a magnetic field in the z-axis, Bimc, at a distance, R, given by the following expression [12]... 

Finally we deal with the magnetic dipolar interaction (9.41) whose general matrix elements are given by... 

We shall examine magnetic dipolar coupling in more detail in Chapter 7, where we show that when the interacting nuclei are in molecules that are in rapid, random motion, as are most small molecules in solution, this interaction averages almost completely to zero. In this chapter and in Chapter 6, we treat only situations in which magnetic dipolar interactions can be ignored. 

Two R1 side chains in a protein, or an R1 side chain and a paramagnetic metal ion in an engineered site, interact by a distance-dependent magnetic dipolar interaction. For the usual case where there is a distribution of interspin distances, the dipolar interaction leads to an EPR... 

Rotational motion of a nitroxide modulates the anisotropic electron-nuclear magnetic dipolar interaction, giving rise to electron relaxation that affects the EPR spectral line shape. At X-band frequency, the spectra are sensitive to motions with correlation times in the range of 10-11 < rc < 10-7, but also reflect the anisotropy of the motion. Figure 5B shows simulated EPR spectra for isotropic motion in the fast, intermediate, and slow motional regimes and illustrates the high sensitivity of the line shape to motional rate. 

Determination of ET rate constants. The proton relaxation of the cyclopentadienyl (cp) ring of the present mixed-valence complex is caused by the magnetic dipolar interaction with the electron spin on the Fe(III) ion of the fetiicenium unit (S=l/2). Then the proton spin-lattice relaxation rate of bfc+, 1/Ti, is represented by ... 

Fig. 3 Experimental and calculated M2 values characterizing the Na- Na magnetic dipolar interactions in crystalline sodium salts. Squares data from [11] (7.04 T) circles new data (9.4 T)...

It has been established that the mobility of protons can be estimated by the detaUed analysis of NMR lineshape. Fen e et al. theoretically treated the influence of isotropic thermal motion upon MAS NMR for spin I = 1/2. When the broadening results from an inhomogeneous magnetic dipolar interaction, the Uneshape is expressed by Lorentzian line with Une width given by the following equation. 

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