Nanoparticles and other nanostructured samples are developing into an increasingly important class of materials. Because of their small size (diameters less than 100 nm), reduced dimensionality, and large surface areas, nanoparticles often exhibit unusual physical, optical, mechanical, and electronic properties. In addition to providing valuable model systems in the pure sciences, nanoparticles are proving useful in technological applications, showing promise as biomedical imaging contrast agents, data storage media, magnetic inks and toners, ferrofluids, and as precursors for advanced compacted materials. Fulfilling this potential depends on characterizing the chemical inhomogeneities of the nanoparticles (and their surfaces) with very high spatial resolution. In this paper I examine the quantitative microanalysis of nanoparticles— electron energy-loss spectroscopy (EELS) and energy-dispersive x-ray spectrometry (EDS)— using transition metal alloy particles (Fig. 1) as a case study.

The microanalysis of nanoparticles presents unique challenges to the analyst because of the very small length scales in the system.