A WIDE BANDWIDTH SPECTROMETER FOR RAPID ULTRASONIC-ABSORPTION MEASUREMENTS IN LIQUIDS

An acoustic near plane-wave absorption spectrometer has been developed for use in small samples of liquid (30 ml) over bandwidths of up to 60 MHz, using a two transducer short-pulse transmission technique. The instrument is controlled by computer, and on-line digital signal processing is used to correct for transducer insertion, radiation coupling, and the transient responses of transmitter and receiver electronics. The raw data acquisition time is short and the instrument in its present form could be used to estimate absorption at 100-ms intervals. The instrument can be used on both stationary chemical systems and systems undergoing chemical reaction. Experimental results are presented that show excellent agreement with absorption measurements by traditional (slower) techniques.