NON-ADDITIVITY OF OH FREQUENCY SHIFTS IN ION WATER SYSTEMS

摘要

The intramolecular OH stretching frequency shift observed for water on formation of 'cation-water...H-bond acceptor' complexes is highly non additive. The uncoupled OH frequency shift has been calculated by ab initio methods for q(+)-OH2 and OH2...q(-) complexes of different geometries and for a series of Mg2+.(H2O)(n)...(H2O)(m) complexes, and we argue that the non-additivity (cooperativity) of the frequency shifts is largely a consequence of the parabolic shape of the frequency versus electric field curves. [References: 34]