ABSTRACT
Gas-phase reactions play a fundamental role in nature, for example atmospheric chemistry [1-5] and interstellar chemistry [6], as well as in many technical processes, for example combustion and exhaust fume cleansing [7-9]. Apart from such practical aspects the study of gas-phase reactions has provided the basis for our understanding of chemical reaction mechanisms on a microscopic level. The typically small particle densities in the gas phase mean that reactions occur in well defined elementary steps, usually not involving more than three particles.
