DIELECTRIC-RELAXATION WITH DIPOLAR SCREENING

The phenomenon of dipolar screening does not appear to have received s ufficient attention in the past, in a manner comparable to charged par ticle screening, and yet it is shown that it is capable of explaining some forms of dielectric response to which no other evident explanatio n exists. While reorientations of mathematical dipoles of zero ''lengt h'' do not entail any charge displacements, physical dipoles of finite length, I, do produce charge displacements and therefore screening. A theory of dipolar screening is presented and it is shown that relativ ely ''dense'' systems give complete screening so that neighbouring dip oles do not ''see'' one another, while in more dilute systems many dip oles fall within a screening radius, R-s, of any one dipole. Dipoles w ithin tend to adopt energetically R-s favoured configuration and the e ntire system ''seizes up'' in a ''domain'', thus reducing the number o f dipoles which can be reoriented at finite frequencies.