The Nonelectrochemical Case

Before discussing the role of roughness in electrochemical systems, we shall consider the experimental data on the response of a QCM immersed in nonconducting liquids, where electrochemical phenomena do not play a role. 

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Experiments in liquids having a wide range of viscosity and density were performed and the response of the QCM analyzed using the theoretical models described in Sec. II.D [24]. Both parameters characterizing the resonator, the shift in fundamental frequency and the width of the resonance were measured simultaneously. The usual form of presenting the experimental data in liquids is to plot the real and the imaginary components of the response of the QCM as a function of the density of the liquid or of the parameter However, these parameters are the natural 

The experimental dependence of the quantity F/f p on the velocity decay length exhibits a sharp increase at low values of 6, followed by a gentle growth at large value of 3. This effect becomes more pronounced with increasing roughness (open circles). 

Dependence (a) of the parameter F jpf and (b) A/7p/ on the velocity decay length in different liquids, for an ideally smooth surface (lines 1), and experimental data for two real surfaces vacuum-sputtered gold (open circles) and electrochemically deposited gold (closed circles). Lines 2 and 3 represent results of parameter fitting (see text). (From Ref. 24.) 

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