QUARTZ CRYSTAL MICROBALANCE RESPONSE OF POLYMER-FILMS WITH UNEVEN THICKNESS COATED ON ELECTRODES

On the basis of theoretical considerations, an attempt was made to give an analytical description of the differential sensitivity function, c(f)(r). Assuming that c(f)(r) is proportional to the square of the vibration amplitude, Gaussian-type and Bessel-type functions, which had been proposed to describe the amplitude distribution of quartz crystal resonators, were tested. Good fits of the experimental data were obtained by using relationships based on these functions. Knowledge of c(f)(r) made it possible to estimate the error of the quartz crystal microbalance (QCM) measurement and/or to calculate the real mass of the deposit in the cases when the electrode surface was not covered uniformly and/or completely. Formulae ware derived for special cases. The problem of QCM measurements of polymer films of uneven thickness on an electrode is discussed.