Dipole image effects

Carnie and Chan (CC) [92,96,97] and Blum and Henderson (BH) [91,94,95] first made important studies of the simplest of nonprimitive models of the electric double layer. They assumed the ions and solvent molecules to be hard spheres with point charges and point dipoles, respectively, and the interface to be a hard smooth charged wall. Image effects were neglected so that the material of the wall was replaced by a vacuum. Also electron overspill from... 

There is also the normal dipole selection rule in operation, as illustrated in Figure 5.48, due to Liith (1981). Any dipole at a surface induces an image charge within the surface. If the dipole orientation is normal to the surface, the effect is enhanced by the image dipole. If, however, the orientation is parallel to the surface, the effect is annihilated by the image dipole. This orientation selection rule thus strongly favours normally oriented dipoles. 

Now consider the pulse sequence in Fig. 10. Each repetition of C spans one rotor period. Between 0 and tr/2, the composite On pulse 90o360igO270o is applied. This composite pulse, which has been commonly referred to as POST, is chosen because it has been shown to compensate for effects of rf inhomogeneity [83], The mirror-image composite pulse is applied between xr/2 and xr. With this particular design of ROCSA, the homonuclear dipole-dipole interaction is considerably suppressed relative to the CSA. 

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