ion microscopy

https://doi.org/10.1351/goldbook.I03221
Use of the secondary ion mass spectrometry (SIMS) technique to obtain micrographs of the elemental (or isotopic) distribution at the surface of a sample with a spatial resolution of 2 ┬Ám or better.
Source:
Orange Book, 2nd ed., p. 249 (http://media.iupac.org/publications/analytical_compendium/)