These premier and carefully made specimens are for resolution testing in the SEM equipped with tungsten, Lab6 or field emission gun (e.g. FEG) emitters. Small and large gold islands provide a variety of gap sizes for both medium and high resolution testing. The high atomic number of gold, and the high secondary electron emissions characteristics make this literally the idea specimen for this kind of instrument performance checking. The SPI Gold on Carbon samples are also an excellent way to judge image quality in the backscattered electron (BSE) detection mode.
For some, at least physically, the most important question, to them, is just what the differences are between these samples in terms of particle size. So while it is the spaces between individual particles that people actually use, since so many people do want to know "particle size". We give that information here, but only because the information is asked for, not because it has any particular meaning in terms of the use of these calibration products.