QUARTZ-CRYSTAL IMPEDANCE STUDIES AT 10 MHZ OF VISCOELASTIC LIQUIDS AND FILMS

A rapid measurement of the components R and X-L of AT-cut quartz cryst al electroacoustic impedance at 10 MHz is reported. Parametric impedan ce plane plots (X-L vs. R) are introduced to analyse the effect of mas s/volume and viscoelastic changes in the films and liquids in contact with the quartz crystal during dynamic chemical or electrochemical pro cesses. Experimental data for selected systems, viscoelastic films and liquids, self-assembled layers and electroactive polymers, are presen ted. These results are discussed on the basis of the model of Granstaf f and Martin to describe the real and imaginary components of the Butt erworth-van Dyke (BVD) equivalen circuit impedance in terms of the den sity, mass and shear modulus of the viscoelastic film or liquid. The p ossibility of separating the inertial (rigid) mass and the viscoelasti c components of quartz impedance when dynamic processes take place is analysed for the selected experimental data presented.