Characterization of transient cavitation in gas sparged solutions exposed to megasonic field using cyclic voltammetry

The application of megasonic energy in semiconductor cleaning solutions has been shown to be very effective in improving the particle removal efficiency (PRE). There has been a significant interest in understanding the phenomena of cavitation and acoustic streaming, which are known to play an important role in particle removal during megasonic cleaning. In the present work, transient cavitation in acoustically (∼1 MHz frequency) irradiated aqueous solutions containing different dissolved gases (Ar, N2 and CO2) has been characterized with a 25 μm diameter microelectrode using high resolution cyclic voltammetry. Specifically, using ferricyanide as an electrochemical probe, current transients are obtained as a function of time. A simple mathematical analysis based on diffusion is used to correlate the collapse characteristics of a transient cavity to the magnitude of current peaks and the time scale of rise and fall in current.

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