MEASUREMENT OF LATTICE-FRINGE VECTORS FROM DIGITAL HREM IMAGES - EXPERIMENTAL PRECISION

The practical measurement of lattice-fringe spacings and angles recorded in digital high-resolution electron micrographs is evaluated experimentally. The method is based on a statistical estimation procedure and involves computer analysis of reciprocal-space parameters. This work concentrates on the analysis of images recorded with slow-scan CCD cameras, but alternative methods of image pick-up are also briefly considered. The method has been successfully applied to images recorded with electron doses smaller than 1 e/Angstrom(2) and for sample dimensions as small as 8 Angstrom across. The practical precision depends on specimen characteristics, electron dose and the size of the measurement area and is in the range of 0.001-0.05 Angstrom for lattice spacings, and 0.1 degrees-0.5 degrees for lattice-plane angles. Finally, the technique is demonstrated in studies of a catalyst system, of a reduced surface oxide phase and of TiO2 and TiN particles.