Dielectric relaxation of short-chain alkyl bromides

The dielectric relaxation of Br(CH₂)_N−1Br, with N = 4 and N = 5, of Br(CH₂)_N−1Br with N = 3 and N = 4 and for 1,2-dichloroethane is deduced using the Jernigan method, where the internal conformational changes are governed by the rotational isomeric state model of Flory. It is found that the dipole moment correlation function for internal conformational changes depends upon the choice of reference coordinate system, and that the dipole moment correlation function cannot be generalized so as to include both overall and internal motions of the chain. An alternative approach, which involves the rotational isomeric state model but conserves angular momentum during an elementary conformational change, is suggested. The available microwave dielectric data on such compounds are considered in relation to the results of the theory.