title: New features of dislocation images in third-generation synchrotron radiation topographs.
abstract: Some aspects of the dislocation contrast observed at third-generation synchrotron radiation set-ups are presented. They can be explained by taking into account angular deviation effects on the beam propagation, which are visible because of the ;almost plane-wave' character of these sources. In particular, we show how the evolution of the direct image width of a dislocation as a function of the sample-to-film distance can allow a complete determination of the Burgers vector, i.e. in sign and modulus. In addition, experimental results obtained in monochromatic beam topography are compared with simulated images calculated assuming plane-wave illumination and are demonstrated to show a satisfactory agreement. The utility of the weak-beam technique in enhancing the spatial resolution is demonstrated and a criterion for the selection of experimental conditions depending upon the required spatial resolution, signal-to-noise ratio and exposure time is presented.
authors.forename: F
authors.initials: F
authors.lastname: Zontone
authors.forename: L
authors.initials: L
authors.lastname: Mancini
authors.forename: R
authors.initials: R
authors.lastname: Barrett
authors.forename: J
authors.initials: J
authors.lastname: Baruchel
authors.forename: J
authors.initials: J
authors.lastname: Härtwig
authors.forename: Y
authors.initials: Y
authors.lastname: Epelboin