Electrostatic phenomena structure

As we shall see in Chapter 3 on electrostatics, these structures can be electrostatically actuated and display a sharp threshold phenomenon called a pull-in instability, where the released structure is pulled down to the ground plane when a certain voltage threshold has been achieved. The pull-in can be observed with a microscope, so that expensive test... 

In all these electrostatic considerations the surface of the ionic crystal was idealized, as described in Sec. IV,2, as if it were cut by means of an ideally sharp razor blade. Our lack of knowledge of the structural deviations of the surface arrangements with respect to the structure inside the crystal renders it impossible for us to make any quantitative or semiquantitative statements regarding the actual adsorption energies caused by electrostatic forces. We can only say that in most ionic crystals negative ions i.e., halide ions or oxide ions, tend to form the outside (adsorbing) surface. We shall have an opportunity (see, for example, Secs. V,5 and VI,5) to revert to this phenomenon. 

The dynamic yield stress (extrapolated to zero shear rates, Figure 8.15) becomes greater with stronger field, indicating the increase of attractive forces between the polarized particles with applied electric field. This phenomenon is attributed to columnar or fibrillar structure formed by the particles as a response to electrostatic interactions induced by electric field. The stronger the field, the larger shear rate is needed to destroy the structure. 

It has been demonstrated that removal of the second proton from 9,9 -bifluorene is nearly as easy as removal of the first (59). It has been suggested that this phenomenon is due to electrostatic stabilization provided by the geometrical arrangement of point charges as provided by a structure such as that observed for 36 (38a). 

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