The low temperature plasma in the Plasma Prep III (SPI) serves a variety of functions as a sample preparation and sample cleaning tool. For detailed microscopy, a low power plasma is used to gently remove an extremely fine layer of surface contamination that can contribute imaging and analytical artifacts in electron microscopy.
A more aggressive etching rate is achieved at higher power. The oxygen (or argon) ion plasma begins to remove sample material, selectively oxidizing organic material or removing oxides, to produce a modified surface. This technique has applications for HR-SEM and TEM imaging. When continued, the etching results in ashing, in which the entire organic portion of a sample is removed, leaving only the inert inorganic residues. This can be useful for studying trace elements or fillers and extenders in organic materials.