Dynamical direct methods for everyone

Recent work has demonstrated that direct methods, using the minimum relative entropy approach, can be applied to strongly dynamical diffraction from bulk inorganic structures. In the present work, the possibility of using intensity data which is thickness averaged, as for a wedge-shaped specimen, is explored. It is shown that for structures which contain a large number of light atoms, well resolved in projection, use of direct methods with thickness averaged data, combined with limited phase information from high-resolution transmission electron microscopy (HRTEM) can indicate the positions of the light atoms. The possibility of using direct methods from thickness-averaged data allows the use of data from conventional microscopes without fine probe capabilities, and is also of importance for use of direct methods with beam-sensitive samples. (C) 1999 Published by Elsevier Science B.V. All rights reserved.