ACOUSTIC-IMPEDANCE OF A LIQUID ON THE SURFACE OF AN AT-QUARTZ

The Shear acoustic impedance of a liquid can be determined from the complex reflection coefficient of the acoustic wave incident on the AT-cut quartz/liquid interface. This complex acoustic coefficient is related to the down shift of the resonant frequence as well as the decrease of the quality factor, due to the liquid load. The effective acoustic impedance measured with the thickness shear mode resonator is shown to be composed of three main components: a preponderant complex component due to viscous coupling between the quartz and the liquid, a pure imaginary additional component due to liquid trapped in the surface irregularities and a pure real additional component due to compressional wave generation in the bulk liquid.