The Chemical Effects of Ultrasound

The chemical effects of ultrasound do not come from a direct interaction with molecular species. Instead, sonochemistry arises from acoustic cavitation: the formation, growth, and implosive collapse of bubbles in a liquid. Cavitational collapse produces intense local heating ( ≈ 5000 K), high pressures ( ≈ 1000 atm), and enormous heating and cooling rates (> 10⁹ K/sec). Acoustic cavitation permits a unique means of interacting energy and matter.

Sonochemistry is in the midst of a renaissance, but remains in its infancy. Its potential impact on the chemical community is large and still developing. Professor Suslick and his team has discovered a variety of chemical effects of ultrasound, including dramatic improvements in both catalytic and stoichiometric reactions. At the same time, they have developed a fundamental understanding of the physical and chemical processes responsible for sonochemistry.

The overall goal in this research is to continue to develop the understanding of the nature and applications of ultrasound in chemical reactivity. The specific objectives in this proposed work fall into four areas: 1) mechanistic and spetroscopic probes of cavitation; 2) homogeneous sonochemistry; 3) heterogeneous sonochemistry and the effect of ultrasound on solids; and 4) novel materials synthesis, both inorganic and biological. 

Within this framework, Professor Suslick's group will continue studies of sonoluminescence as a means of probing the conditions reaching during cavitational collapse. They will expand their study of homogeneous sonochemistry, including various organic and organometallic compounds. They will further examine the activation of metal surfaces for both synthetic and catalytic applications and will extend this work to non-metallic surfaces. Heterogeneous and homogeneous sonocatalytic systems will continue to be a major interest. They will also explore the use of ultrasound for the synthesis of novel materials. Their very recent successes, which include the diverse preparation of metallic glass powders and of proteinaceous microspheres, will be further explored.