SPI Supplies Molybdenum Trioxide Specimen on 2.3 mm Copper Grid in a Capsule
Molybdenum trioxide specimen
2.3 mm copper grid shipped in a capsule
For studies involving selected area electron diffraction, there is a "rotation" of the image when switching from the selected area bright field mode to the diffraction mode. Often times there is a great need to know precisely, the amount of this rotation, in order to make the proper interpretation of results.
The easiest way to do this is to first capture an image of the diffraction pattern of the crystal being characterized and then record on a second (or as a double exposure) image. A good test sample must have crystals of well-defined faces (for the known orientation) and also, a sharp well-defined diffraction pattern, and at the same time, the crystal must be robust enough so that it is not quickly degraded by the beam.
Some years ago it was discovered that molybdenum trioxide is the ideal kind of specimen for this kind of application. For those wanting to either make their own or else use the production of such a sample as part of a class room exercise, see the technical note.