![Loading...](https://www.agarscientific.com/static/version1720620014/frontend/Pixiemedia/Agar/en_GB/images/loader-1.gif)
A test specimen with molybdenum trioxide crystals on a carbon film is good for the calibration of the image-diffraction rotation angle in TEM and STEM mode. Molybdenum trioxide is pseudo-orthorhombic (lattice parameters a 0.397nm, b 1.385nm and c 0.370nm). From a double-exposure, or the overlaying of an image and diffraction pattern, the rotation angle can be established.