1ST TOPOGRAPHIC RESULTS AT THE EUROPEAN SYNCHROTRON-RADIATION FACILITY

The first topographic observations performed at the ESRF using the whi te beam of the ID11 Materials Science wiggler beamline, are described. Several plate-shaped single crystals (Si, Ge, quartz, Ga- YIG, Fe-3%S i, Al-Pd-Mn quasicrystals, ...), with thicknesses ranging from 0.3 mm (Ge) to 1.4 mm (Fe-3%Si) and even 1 cm (Si), are investigated in the t ransmission mode. The heat load associated with the wiggler beam has t o be reduced. The main features of the topographs are the short exposu re times (almost-equal-to 5 x 10(-3) to 10(1) s), the high photon ener gies corresponding to the recorded Bragg spots (up to almost-equal-to 110 keV), and the good spatial resolution obtained even when setting t he film far (from 17 cm to more than 1 m) from the sample. The contras t of dislocation images is consistent with the presently accepted theo retical models.