Acoustical absorption spectroscopy of liquids between 0.15 and 3000 MHz: II. Ultrasonic pulse transmission methods

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Abstract
Two methods are described which allow precise measurements of the ultrasonic absorption coefficient of liquids between about 5 and 400 MHz and 1 and 50 MHz, respectively. In both cases RF substitution techniques are applied to determine the attenuation of pulsed signals transmitted through the sample cell. In the former method a cell with variable spacing of the piezoelectric transmitter and receiver crystal is used and the measurements are automatically driven by a process control computer. The latter method is based on a cell of fixed pathlength, using a simple electronic set-up and a manual mode of operation. The construction of the cells is given in detail and the relative merits and limitations of the two methods are briefly discussed. Examples of acoustic absorption spectra are presented to demonstrate the accuracy of measurements.