Modification of a TEM‐goniometer specimen holder to enable beam current measurements in a (S)TEM for use in quantitative X‐ray microanalysis

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Abstract
In order to have available a specimen holder suited to measure the beam current as is often required in quantitative electron probe X‐ray microanalysis, the rod of a low background beryllium specimen holder of a transmission electron microscope was modified. The tip was electrically insulated from the mass of the microscope and connected electrically to the central contact of a BNC connector mounted on the specimen holder handle. With this modified specimen holder the current absorbed by the specimen and/or the specimen holder could be measured easily and accurately. The modified specimen holder has been used to measure the beam current stability of an analytical electron microscope under various conditions. Data were obtained for tungsten as well as lanthanum hexaboride cathodes. Small changes to other types of specimen tips made it possible to exchange these for the low background tip.