The physical mechanisms underlying the surface based mass spectrometry techniques of atomic SIMS, MALDI and cluster SIMS are discussed along with the relation of the physics to the measured quantities. In particular, there are at least two types of motion resulting from cluster bombardment in SIMS. One scenario involves the individual atoms in the cluster initiating collision cascades similar to atomic bombardment. The second mechanism involves a mesoscale motion of the cluster as a whole. This mesoscale motion can induce an organized flow of the ejected material in a plume. (c) 2006 Elsevier B.V. All rights reserved.