I have the TEM diffraction pattern and I don t know how to calculate the lattice parameters and what information I should ask the operator for the calculation.
Use SingleCrystal, Diffraction Ring Profiler, GDIS, JEMS, Mac Tempas. Good luck! http://www.crystalmaker.com/ http://www.softpedia.com/get/Multimedia/Graphic/Graphic-Others/Diffraction-Ring-Profiler.shtml http://gdis.sourceforge.net/ http://cimewww.epfl.ch/people/stadelmann/home.htm http://www.totalresolution.com/CrystalKit.html
It depends on the crystal system but a good way of measuring d-spacings is in gatan digital micrograph as long as it has the calibrations in the software already. You just draw a line for an intensity profile across the reflections and measure peak to peak by dragging the cursor over the profile. This all depends on systematic absences and orientation of the SAED pattern, but if a*, b*, or c* is in the pattern, one of these will be closest repeat in the pattern. In the example I attached, the closely spaced reflections from the upper left to lower right represent b* of a monoclinic mineral in this case, and from the profile the b = ~19 angstroms. You can also do this in imageJ as long as there's a scale bar in the image to calibrate the pixels to. For unknowns you will just need to index the patterns as others have mentioned.