Quartz crystal impedance studies at 10 MHz of viscoelastic liquids and films

Abstract

A rapid measurement of the components R and X_L of AT-cut quartz crystal electroacoustic impedance at 10 MHz is reported. Parametric impedance plane plots (X_Lvs. R) are introduced to analyse the effect of mass/volume and viscoelastic changes in the films and liquids in contact with the quartz crystal during dynamic chemical or electrochemical processes. Experimentaldata for selected systems, viscoelastic films and liquids, self-assembledlayers and electroactive polymers, are presented. These results are discussedon the basis of the model of Granstaff and Martin to describe the real andimaginary components of the Butterworth–van Dyke (BVD) equivalen circuit impedance in terms of the density, mass and shear modulus of the viscoelastic film or liquid. The possibility of separating the inertial (rigid) mass and the viscoelastic components of quartz impedance when dynamic processes take place is analysed for the selected experimental data presented.