HIGH-FREQUENCY IMPEDANCE ANALYSIS OF QUARTZ-CRYSTAL MICROBALANCES .1. GENERAL-CONSIDERATIONS

Impedance analysis of AT and BT cut quartz of 5- and 6.19-MHz nominal frequencies under different conditions of operation is shown. Conditions are as follows: in air, in contact with a liquid, and simultaneous electrochemical deposition of viscoelastic layers in solution, Cu, Ag, poly(pyrrole tosylate), and poly(pyrrole tetrafluoroborate). Comparison with prevailing theories is included. It is shown that inductance can be measured accurately, that inductance calibration is preferable when resistance is large, that surface structure can be studied by impedance analysis, that inductance is a linear function of mass for elastic and viscoelastic films, and that the calibration range of EQCMs is extended by impedance analysis. These advantages result from the separation of mass and energy loss measurements by decomposition of the composite resonator admittance into inductive and resistive components, respectively.