Chemical reactions of atoms with molecules in colliding beams

In investigations into the nature of chemical reaction the emphasis has changed from experiments which determine bulk properties to those at the microscopic level. The role of the crossed beam approach in this fundamental study is discussed. The methods available for the production and detection of atomic and molecular beams, including analysis or selection of both the translational energy and internal state distributions, are considered. Selected experiments are used to highlight the development of the crossed beam techniques and to illustrate the type and quality of the information that can be deduced about reaction dynamics. This leads to the formulation of reaction models. The achievements of theoretical methods and their ability to predict reaction behaviour are reviewed. Finally, current developments in experimental techniques using laser technology are presented.