Acoustic electroacoustic spectroscopy

Recent advances have been made in the theory and application of acoustic and electroacoustic spectroscopies for measuring the particle size distribution (PSD) and -potential of colloidal suspensions, respectively.67-69 To date, the use of acoustics has been confined mainly to industrial applications, despite the clear potential for the technique to characterize colloids with environmental or agricultural significance. 

Dukhin, A.S. and Goetz, P.J., Acoustic and electroacoustic spectroscopy for characterizing concentrated dispersions and emulsions, Adv. Colloid Interface Sci., 92, 73-132, 2001. 

Guerin, M. and Seaman, J.C., Characterizing clay mineral suspensions using acoustic and electroacoustic spectroscopy—a review. Clays Clay Miner., 52, 145, 2004. 

Acoustic and Electroacoustic Spectroscopy for Characterizing Emulsions and Microemulsions... 

The contribution of electrokinetic losses to the total sound attenuation is almost always negligibly small (9) and will be neglected. This opens an opportunity to separate acoustic spectroscopy from electroacoustic spectroscopy because acoustic attenuation spectra are independent of the electric properties of the dispersed system. 

In acoustic spectroscopy sound is utilized as both the excitation and the measured variable, and therefore there is but one basic implementation. In contrast, electroacoustic spectroscopy deals with the interaction of electric and acoustic fields and therefore there are two possible implementations. One can apply a sound field and measure the resultant electric field which is referred to as the colloid vibration potential (CVP), or conversely one can apply an electric field and measure the resultant acoustic field which is referred to as the ESA. 

The combination of acoustic and electroacoustic spectroscopy provides a much more reliable and complete characterization of the disperse system than either one of those techniques separately. Electroacoustic phenomena are more complicated to interpret than acoustic phenomena because an additional field (electric) is involved. This problem becomes even more pronounced for a concentrated system. It makes acoustics favorable for characterizing particle size, whereas electroacoustics yields electric surface properties. 

Reproduced from Characterization of CMP Slurries A New Composite Method Comprised of Acoustic and Electroacoustic Spectroscopy and Sedimentation Monitored with Ultrasound, Dispersion Technology Inc., http //www.dispersion.com/characterization-of-cmp-slurries-part2... 

Long, R.B. (1981). The Concept of Asphaltenes, In Chemistry cf Asphaltenes, J.W. Bunger N.C. Li (Eds.), 17-27, American Chemical Society, Washington DC, USA Magual, A. Horvath-Szabo, G. Mashyah, J.H (2005). Acoustic and Electroacoustic Spectroscopy of Water-in-EHluted-Bitumen Emulsions. Langmuir, Vol.21, No.l9, pp. 8649-8657... 

Different from acoustic attenuation spectroscopy, in electroacoustic spectral analysis, sound waves are generated by an applied high frequency electric field across a colloidal suspension and subsequently detected. This is called the electrokinetic sonic amplitude effect (ESA) [38]. These sound waves arise because the alternating electric field pushes the suspended particle forwards and backwards. By measuring the magnitude and phase angle of the sound waves at multiple frequencies (typically from 1-10 MHz), the particle dynamic mobility, Pd, can be determined, provided the concentration and the density of the... 

It is also worth mentioning that particle size can also be estimated from electroacoustic measurements of the phase angle of CVP. In this case measurements done at a single frequency yield mean particle size, while in the case of multiple frequencies particle size distribution can be obtained. Acoustic spectroscopy is, however, more practical for particle size analysis than for electroacoustic CVP measurement. 

Whereas acoustic spectroscopy describes the combined effect of the six separate loss mechanisms, electroacoustic... 

---