The Chemical History of a Bubble

. Scientists from many disciplines, and even nonscientists, have been and continue to be intrigued by the consequences of dynamic bubbles in liquids. As chemists, we are fascinated by the high energy reactions and processes that occur during acoustic cavitation and by the use of SL as a spectroscopic probe of the events during cavitation. Within the chemical realm of SL and cavitation there are many interesting questions that are now answered but also many that remain to be explored, so we hope that this Account reveals to the reader some of the most fascinating of those curiosities as we explore the chemical history of a bubble. The high energy species produced inside collapsing bubbles also lead to secondary reactions from the high energy species created within the collapsing bubble diffusing into the bulk liquid and expanding the range of sonochemical reactions observed, especially in redox reactions relevant to nanomaterials synthesis. Bubbles near solid surfaces deform upon collapse, which lessens the internal heating within the bubble, as shown by SL studies, but introduces important mechanical consequences in terms of surface damage and increased surface reactivity. Our understanding of the conditions created during cavitation has informed the applications of ultrasound to a wide range of chemical applications, from nanomaterials to synthetically useful organic reactions to biomedical and pharmaceutical uses. Indeed, we echo Michael Faraday's observation concerning a candle flame, "There is not a law under which any part of this universe is governed which does not come into play and is touched upon in these phenomena." ( Faraday , M. The Chemical History of a Candle ; Harper & Brothers : New York , 1861 ).