Sonochemistry and sonoprocessing: the link, the trends and (probably) the future.

Traditionally the community of scientists involved with ultrasound has been divided broadly into those who use it as a measurement device with no effect on the medium (high frequency low power ultrasound e.g. non-destructive testing) and those who use it to produce physical or chemical effects in a medium (higher power low frequency ultrasound e.g. sonochemistry). Divisions also exist within the broad spectrum of those involved with the latter. In the early days of sonochemistry this did not prove to be a major problem, the subject was new and the field was expanding within the chemistry community. However at a point some years ago Jean-Louis Luche made the very important observation that sonochemistry applications could be subdivided into reactions which were the result of "true" and "false" effects [Synthetic Organic Chemistry by J.-L. Luche, 1998, p. 376]. Essentially these terms referred to real chemical effects induced by cavitation and those effects that could be mainly ascribed to the mechanical impact of bubble collapse. These mechanical effects have not held the interest of synthetic chemists as much as the so-called true ones but nevertheless they are certainly important in areas such as processing. In this paper I will attempt to show that there are links that can be made across many of the ultrasound "disciplines" and that these links can only serve to strengthen research in the general area of power ultrasound. If research on power ultrasound is strong then research into "pure" sonochemistry will also flourish and "false" sonochemistry will be born again as a significant research area.