Correlation between Sonoluminescence, Sonochemistry and Cavitation Noise Spectra

The Behavior of Acoustic Bubbles in Aqueous Solutions Containing Soluble Polymers

“…7,9,14 MBSL enhancement by charged surface active species has been attributed to either electrostatic interactions between charged bubbles increasing the number of bubbles that are directly affected by the acoustic field 4,10 or surfactant adsorption onto the bubble surface acting to retard bubble coalescence, resulting in more bubbles of the size capable of generating SL. 15 Recent work suggests both processes can be in operation. 16 The present study reports on the effects of a water-soluble polymer (PVP) on the SL intensity generated in aqueous solutions.…”

“…A number of studies have examined the effects of surface-active solutes on multibubble sonoluminescence (MBSL) generated in aqueous solutions exposed to ultrasound. − Depending on the nature of the solute in solution and the type of cavitation generated by the ultrasound, either suppression or enhancement of the MBSL signal can be observed. , In general, in aqueous systems exposed to high frequency ultrasound, volatile surface-active solutes cause SL quenching. This quenching of SL has been linked to the thermal decomposition of solutes and the accumulation of decomposition products inside relatively long-lived bubbles undergoing “repetitive transient” cavitation. ,− At lower frequency (e.g., 20 kHz), the same degree of quenching is generally not observed, reflecting that SL emission is predominantly from bubbles with a lifetime of only a few acoustic cycles. ,, MBSL enhancement by charged surface active species has been attributed to either electrostatic interactions between charged bubbles increasing the number of bubbles that are directly affected by the acoustic field , or surfactant adsorption onto the bubble surface acting to retard bubble coalescence, resulting in more bubbles of the size capable of generating SL . Recent work suggests both processes can be in operation …”

The effect of surface active solutes on bubbles in an acoustic field

“…Segabarth et al 97 have suggested that the observed effect may not be related to the ''de-clustering'' of the bubbles, but may be related to hindrance in bubble coalescence caused by surfactant adsorption. However, further work on the effect of surface active solutes on acoustic emission spectra provides strong support of the ''de-clustering'' hypothesis, which will be discussed in the next section.…”

“…At 20 kHz, the asymmetric collapse of ''transient'' bubbles generates a broadband emission, whereas the relatively symmetric collapse of ''stable'' bubbles emit harmonics of the fundamental frequency. Segebarth et al 97 demonstrated that the acoustic emission generated by cavitation bubbles can also be used to study the effect of solutes on cavitation. They reported that both sonoluminescence and sonochemistry can be correlated with the full width at maximum of the second harmonic of acoustic emission observed at 515 kHz ultrasound frequency.…”

A comparative sonochemical reaction that is independent of the intensity of ultrasound and the geometry of the exposure apparatus

“…For example, varying the ultrasound frequency in a sonochemical experiment results in a change in the cavitation bubble field such that the energy being converted by cavitation bubbles in producing a sonochemical effect is not known. To date, the problem of quantifying sonochemistry remains mostly unresolved, although there have been some interesting developments in this area of research over the past decade or so in both multi-bubble and single bubble sonochemistry [3,[10][11][12][13][14][15].…”