title: Ultrasound artificially nucleated bubbles and their sonochemical radical production.
abstract: We describe the ejection of bubbles from air-filled pits micromachined on a silicon surface when exposed to ultrasound at a frequency of approximately 200 kHz. As the pressure amplitude is increased the bubbles ejected from the micropits tend to be larger and they interact in complex ways. With more than one pit, there is a threshold pressure beyond which the bubbles follow a trajectory parallel to the substrate surface and converge at the center point of the pit array. We have determined the size distribution of bubbles ejected from one, two and three pits, for three different pressure amplitudes and correlated them with sonochemical OH· radical production. Experimental evidence of shock wave emission from the bubble clusters, deformed bubble shapes and jetting events that might lead to surface erosion are presented. We describe numerical simulations of sonochemical conversion using the empirical bubble size distributions, and compare the calculated values with experimental results.
authors.affiliation: Mesoscale Chemical Systems Group, MESA+ Research Institute, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands. d.fernandezrivas@utwente.nl
authors.forename: David
authors.initials: D
authors.lastname: Fernandez Rivas
authors.forename: Laura
authors.initials: L
authors.lastname: Stricker
authors.forename: Aaldert G
authors.initials: AG
authors.lastname: Zijlstra
authors.forename: Han J G E
authors.initials: HJ
authors.lastname: Gardeniers
authors.forename: Detlef
authors.initials: D
authors.lastname: Lohse
authors.forename: Andrea
authors.initials: A
authors.lastname: Prosperetti