Dimerization of impurity-vacancy dipoles in alkali halides

The aggregation of impurity-vacancy dipoles in KCl and NaCl doped with various divalent impurities is shown to follow initial second-order kinetics. This is accomplished by including dissociation as well as formation of dimers in the theory of dipole decay. An apparent initial third-order process, reported by many workers over the past dozen years, arose because dissociation was neglected in the analyses previously made.