Quality Assessment of Sapphire Wafers for X-Ray Crystal Optics Using White Beam Synchrotron X-Ray Topography

Nuclear forward and inelastic spectroscopy on 125 Te and Sb 2 125 Te 3

“…A resolution of 0.2 meV at 35.4 keV requires 2 • 10 8 perfectly parallel reflecting planes which corresponds to about 3 mm thickness of a dislocation free crystal. As reported from topography studies [36], the quality of available sapphire crystals is in general nowadays much worse than this requirement. The second reason could be the temperature gradient in the crystal over the sapphire thickness due to heat load from the impinging X-ray beam.…”

Nuclear resonant forward scattering of synchrotron radiation from 121 Sb at 37.13 keV

“…Very attractive in this respect are sapphire (α-Al 2 O 3 ) single crystals, which unlike Si have also high reflectivity for X-rays above 30 keV. The disadvantage is that the crystal perfection, which is mandatory to achieve a high-energy resolution, in general is not as high for sapphire as for silicon [16,22]. The application of sapphire as a high-resolution monochromator was demonstrated in NFS studies on 161 Dy at 25.61 keV [23].…”

“…This is first of all due to the presence of some dislocations in the sapphire crystal. A high-quality crystal from Crystal Systems Inc. has been chosen among others using X-ray topography [22]. The measured dislocation density was about 10 2 /cm 2 .…”