Frontiers of analytical electron microscopy with special reference to cluster and interface problems

This paper discusses two main aspects of high spatial resolution analytical electron microscopy (AEM): (i) the relationship between the macroscopic properties of the material and its local chemistry as determined from X-ray or EELS spectroscopies, connected with the sampling procedure; (ii) the accessible detection limits, i.e. the frontiers of the technique which are determined by different considerations involving the physics of the interaction, the specimen and the instrument. A graphical representation of the important factors defining the domain of accessible performance, using a chart (Concentration, Resolution), is introduced. Its range of application covers many practical situations encountered in materials science: two representative ones, relative to small metal clusters and to segregation on an interface, are discussed extensively in order to demonstrate the usefulness of the present description.