Proton Microprobe Geological Specimen Prerequisites
Grains should be placed in epoxy mounts as for EPMA. The diameter of these circular mounts should be 1.0 or 1.25 inch and the thickness less than 0.5 inch. Alternatively polished thin sections on glass slides (1 inch x 2 inch) are acceptable.
In the first case grains to be analyzed should be at least 50um thick to ensure the beam is stopped within the grain. Similarly thin polished sections should be at least 50 um thick so that the beam does not induce X-rays from the substrate.
All samples must be carbon-coated precisely as for EPMA to ensure no charging occurs.
Maps and pictures of regions of interest must be provided so that the maximum time may be devoted to actual analysis and the minimum to searching for the portions of interest (and to analyzing the wrong portions!).