Dielectric saturation in water as quantitative measure of formation of well-defined hydration shells of ions at various temperatures and pressures. Vapor-liquid equilibrium case

摘要

Static electric permittivity ?μ of water at equilibrium saturated vapor pressures in electric field in the range 10~8 < E < 10~(11) V m~(- 1) was calculated. A quantitative measure of the dielectric saturation phenomenon was introduced. It is found that, according to the definition of this measure, well-defined first hydration shells of numerous ions investigated by X-ray and neutron scattering methods described in literature are electrically saturated, and that at various conditions. Calculations show that around some ions, including Ag~+, whose hydration shells are not saturated at ambient conditions, dielectric saturation of water can be achieved by increasing temperature and pressure up to the values not far from the critical ones. This is compared with extended X-ray absorption fine structure (EXAFS) and XAFS data for Ag~+ and Rb~+ found in literature.