Contact and surface impedances on humid mica and glass

Impedance measurements in the frequency range 10/sup -2/-10/sup 4/ Hz are reported on humid surfaces of ruby mica and glass, with the relative humidity (RH) of the ambient air as a variable parameter. Both the interfacial impedance of the one-dimensional contacts to the surface conducting layer and the surface impedance proper are found to be strongly dispersive, contrary to the usual assumption that surface conduction or surface leakage entails ohmic direct current phenomena. The glass samples were specially shaped to enhance the surface contribution in comparison with the contact impedance. Equivalent circuits are derived, and their physical significance is discussed. The amplitude of the rate processes is approximately exponential with RH.<
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