INFLUENCE OF THE SURFACE MICROSTRUCTURE ON THE COUPLING BETWEEN A QUARTZ OSCILLATOR AND A LIQUID

A quartz oscillator, operated with one of its faces in contact with a liquid, can be used as a highly sensitive microbalance. When used together with an electronic driver circuit, frequency changes will not only reflect changes of vibrating rigid mass but also detect changes of the surface microstructure. Using impedance spectroscopy we have analyzed the influence of the surface microstructure on the frequency changes. A liquid that is rigidly coupled to the surface by inclusion into voids or narrow channels can be discerned from a liquid that is viscously coupled to the surface. This analysis is shown for silver surfaces, roughened by several oxidation and reduction cycles, in chloride ion containing solutions.