Gentle Asher for pre-cleaning specimens
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Electron microscope (EM) imaging is often degraded by hydrocarbon contamination (HC) carried into the EM chamber on specimens or specimen mounts. The Gentle Asher, with an Evactron® De-Contaminator (D-C) attached, can be used to preclean samples with high HC contamination levels in order to prevent contaminant introduction into the EM chamber. The same downstream Evactron operating concept of oxygen radicals gently ashing HCs, which occurs while the Evactron D-C is cleaning the EM chamber, will also occur in the Gentle Asher. Samples can also be stored in the Gentle Asher if it is fitted with a dry pump and nitrogen purging.
The Gentle Asher is intended to operate with an Evactron D-C to clean samples and sample holders when the Evactron D-C is not being used for its principal purpose of removing HC contamination from EM chambers. In many situations, after the EM chamber has been returned to less than visible contamination levels, Evactron use is only periodically necessary. During these periods, the Evactron D-C can be used with the Gentle Asher to clean samples and sample holders. The Gentle Asher/Evactron D-C combination is not a "plasma cleaner" in the usual sense. Samples are cleaned by downstream ashing in the Evactron process using room air as the oxygen source. Specialty gases and gas mixtures are unnecessary. Typical "plasma cleaners" rely on energetic ions which remove HC through sputter etching. However, sputter etching can damage specimens. By contrast, the Evactron process delicately oxidizes HC into H2O, CO, and CO2, which are subsequently pumped out of the chamber. |
