QED v 1.0: a software package for quantitative electron diffraction data treatment.

A new software package for quantitative electron diffraction data treatment of unknown structures is described. No "a priori" information is required by the package which is able to perform in successive steps the 2-D indexing of digitised diffraction patterns, the extraction of the intensity of the collected reflections and the 3-D indexing of all recorded patterns, giving as results the lattice parameters of the investigated structure and a series of data files (one for each diffraction pattern) containing the measured intensities and the relative e.s.d.s of the 3-D indexed reflections. The software package is mainly conceived for the treatment of diffraction patterns taken with a Gatan CCD Slow-Scan Camera, but it can also deal with generic digitised plates. The program is designed to extract intensity data suitable for structure solution techniques in electron crystallography. The integration routine is optimised for a correct background evaluation, a necessary condition to deal with weak spots of irregular shape and an intensity just above the background.