Iridium is useful for coating samples before electron microscopy. The Cressington 208 iridium sputtering tool provides very smooth, conformal coatings which are free of the grain structure found in films of Au or Au-Pd. Chromium would also be a good choice for coating SEM samples, but iridium oxidizes much more slowly, and so has an advantage over fine-grained chromium films.
A sputter coater for gold is located next to the chromium system. Gold is used for coating electron-beam resist before lithography, but is not a good choice for SEM samples.