Field-dependent Mechanism of Anomalous Proton Conductivity and the Polarizability of Hydrogen Bonds with Tunneling Protons

Abstract

The displacement of the excess charge of the proton in acid solutions is caused by a structure migration of groupings H₅O₂ ⁺ or H₉O₄ ⁺ . The processes which take place during structure migration are discussed on the basis of results gained in IR-investigations. In an electrical field the structure migration is given a preferred direction. The hydrogen bond with the tunneling proton in H₅O₂ ⁺ and the grouping H₃O⁺ in H₅O₂ ⁺ become polarized. Comparison of both polarizabilities demonstrates that, contrary to previous assumptions, the polarization of the hydrogen bond is the field-dependent mechanism. This conclusion is reached upon calculating the polarizability of the hydrogen bond with a symmetrical double minimum potential well. It is shown that the polarizability is extremely large, being approximately two orders of magnitude greater than that of H₃O⁺ . Despite the large polarizability, the shift of the weights of the proton boundary structures is very small for the external fields usually applied in conductivity measurements. It is demonstrated, however, that this slight shift is large enough for the structure diffusion to obtain a preferred direction consistent with the anomalous high proton conductivity.