Sonochemistry acoustic-pressure amplitude

The human ear can be excited by an energy as low as 10 J, corresponding to the work spent in lifting a mass of 10 g by 1 mm against gravity. Our perception of sound-wave strength is linked to acoustic intensity, i.e., the acoustic pressure amplitude of the wave (Pa, in Pa or bars). Normal speech corresponds to a pressure of lO bar. In sonochemistry, pressures of a few bars are commonly used, which means that sonochemists deal with extremely non-linear systems. In the case of a progressive planar or spherical wave,i the acoustic pressure and intensity (in W m"2) of the ultrasoimd are linked as in Eq. 2 ... 

Fig. 1.2 Numerically simulated frequency spectra of the hydrophone signal due to acoustic cavitation noise. The driving ultrasound is 515 kHz in frequency and 2.6 bar in pressure amplitude, (a) For stable cavitation bubbles of 1.5 pm in ambient radius, (b) For transient cavitation bubbles of 3 pm in ambient radius. Reprinted from Ultrasonics Sonochemistry, vol. 17, K. Yasui, T. Tuziuti, J. Lee, T. Kozuka, A. Towata, and Y. lida, Numerical simulations of acoustic cavitation noise with the temporal fluctuation in the number of bubbles, pp. 460-472, Copyright (2010), with permission from Elsevier...

Fig. 1.4 The calculated results for one acoustic cycle when a bubble in water at 3 °C is irradiated by an ultrasonic wave of 52 kHz and 1.52 bar in frequency and pressure amplitude, respectively. The ambient bubble radius is 3.6 pm. (a) The bubble radius, (b) The dissolution rate of OH radicals into the liquid from the interior of the bubble (solid line) and its time integral (dotted line). Reprinted with permission from Yasui K, Tuziuti T, Sivaknmar M, Iida Y (2005) Theoretical study of single-bubble sonochemistry. J Chem Phys 122 224706. Copyright 2005, American Institute of Physics...

Hatanaka et al. [50], Didenko and Suslick [51], and Koda et al. [52] reported the experiment of chemical reactions in a single-bubble system called single-bubble sonochemistry. Didenko and Suslick [51] reported that the amount of OH radicals produced by a single bubble per acoustic cycle was about 10s 106 molecules at 52 kHz and 1.3 1.55 bar in ultrasonic frequency and pressure amplitude, respectively. The result of a numerical simulation shown in Fig. 1.4 [43] is under the condition of the experiment of Didenko and Suslick [51]. The amount of OH... 

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