Interchange energy

Because both spins are in the transverse plane and transition energy levels are matched, energy can be transferred from the protons to the nuclei. In this manner the rate of repolarization is controlled by rather than by Because the protons can interchange energy by spin-diffusion only a single-proton exists and its value is usually on the order of 1 s. As a result the preparation delay can be reduced from 10 s to about 5 s increasing the number of transients, which can be acquired by two or more orders of magnitude. 

The interchange energy of electrons is in general the energy of the non-polar or shared-electron chemical bond. 

This, the naive potential function, is also shown in figure 11. It corresponds to a relatively small attraction, so that the conclusion can be drawn that in the hydrogen molecule the interchange energy of the two electrons is the principal cause of the forces leading to molecule formation. 

The additional Helmholtz energy responsible for this secondary lattice can be expressed by using Equation (12) for binary Ising mixture with Xi, x2 replaced by and (1 — Finally, we obtain the temperature-dependent interchange energy that is quadratic to the inverse temperature. 

In order to explain the experimental behavior found of X for PVP in the different mixtures, the polarizability was taken into account because of the methyl groups substituents of the aromatic ring. It is possible to And changes in the nature of the interactions between the polar solute, 2 - propanol, and the aromatic component in the binary mixtures and that these changes affect the X values. The importance of dipole - induced dipole interactions and steric factors in the formation of a molecular complex between a polar component and a non - polar aromatic solvent has been emphasized on the basis of NMR studies [111, 112], The molecular interactions in binary liquid mixtures have also been studied on the basis of viscosity measurements. The viscosity data have also been used by Yadava et al. [113,114] to obtain a value for the interchange energy (Wvisc) [115] This parameter can be estimated by the equation ... 

Aromatic solvent Molar volume32 (cm3 g 1 mol) X (mgg ) d parameter at 50% mol Wvisc Interchange energy (J mol-1)... 

Table 1.7 shows the values of the preferential adsorption coefficient X, in mg (mg/g) the molar volumes of the aromatic solvents d - parameters and the values of the interchange energy (Wvisc) of the aromatic solvents - 2 - propanol mixtures. 

W mass of seed material or interchange energy X characteristic length of crystal... 

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