Accurate measurements of crystal structure factors using a FEG electron microscope

An experimental procedure for the accurate measurement of crystal structure factors is described. This procedure is based on the use of a field emission gun electron microscope equipped with a Gatan Imaging Filter (GIF) system. The slow-scan CCD camera of the GIF system is first characterized and a constrained least squares restoration scheme is used for the deconvolution of the experimentally recorded raw elastic CBED patterns. The procedure has been applied for the accurate measurement of the (111) and (222) structure factors of silicon single crystal. A residual chi(2) value of 2.87 is achieved and the determined structure factors agree well with previous measurements using X-ray and electron diffraction techniques. (C) 1997 Elsevier Science Ltd. All rights reserved.