Nuclear microprobe — Principle and equipment

The particle or radiation emissions that accompany the penetration of light ions into matter, at incident energies of the order of a few mega-electronvolts, have given rise to a number of elemental assay methods. These methods are often used for surface or thin-film analysis. Focusing these micrometer-scale particle beams on samples has led to the development of a generation of instruments known as nuclear microprobes. The first of these appeared in the UK in 1969 [1] . Since then, some sixty devices of this type have been developed worldwide, mainly in technologically advanced countries such as Europe, the United States, Japan and Australia. The recent commissioning of new facilities equipped with the latest-generation gas pedals attests to the vitality of this field. Beam sizes now reach a few hundred nanometers, or even less for low-current applications.

A nuclear microprobe can be considered as a means of elemental analysis, structural characterization or as a tool for local energy or charge deposition. These multiple faces reflect the exemplary possibilities offered by high-energy ion microbeams. Thanks to the choice of beam characteristics (type and energy of the ions), the experimenter can control the implementation of the interaction. This makes it possible to achieve very fine lateral localization, directly linked to beam size, and to access the micro-distribution of elements in three dimensions.

In the second part , nuclear microprobe applications are described.