Small Bragg-plane slope errors revealed in synthetic diamond crystals

Abstract

Wavefront-preserving X-ray diamond crystal optics are essential for numerous applications in X-ray science. Perfect crystals with flat Bragg planes are a prerequisite for wavefront preservation in Bragg diffraction. However, this condition is difficult to realize in practice because of inevitable crystal imperfections. Here, X-ray rocking curve imaging is used to study the smallest achievable Bragg-plane slope errors in the best presently available synthetic diamond crystals and how they compare with those of perfect silicon crystals. It is shown that the smallest specific slope errors in the best diamond crystals are about 0.08 (3) µrad mm−2. These errors are only 50% larger than the 0.05 (2) µrad mm−2 specific slope errors measured in perfect silicon crystals. High-temperature annealing at 1450°C of almost flawless diamond crystals reduces the slope errors very close to those of silicon. Further investigations are in progress to establish the wavefront-preservation properties of these crystals.

Large‐Sized X‐ray Optics Quality Chemical Vapor Deposition Diamond

“…Figure 3 shows 8 keV X-ray 400 Bragg reflection RCI maps of the N1 CVD diamond plate obtained in a double crystal close to a nondispersive arrangement. [22] The homogeneity of the FWHM map through the area correlates well with the X-ray image in Figure 1b. In the defect-free areas, the Bragg reflection width (FWHM) is almost theoretical, which is in agreement with the FWHM of RC shown in Figure 2d.…”

Diamond channel-cut crystals for high-heat-load beam-multiplexing narrow-band X-ray monochromators

“…Apparently, laser machining is accompanied by graphitization of the diamond surface. To erase the blackening, we anneal the crystals in air at a temperature of 630-650 C for 3 h, as in our previous and recent studies (Kolodziej et al, 2016;Pradhan et al, 2020). After annealing, the blackening has vanished, as seen on the photographs in Figs.…”

“…In this technique, Bragg reflection images of the crystal under study are measured with a pixel X-ray detector, with images being taken sequentially at different incidence angles to the reflecting atomic planes of the well collimated X-rays; Bragg reflection maps are calculated for the reflection peak intensities, angular widths and angular positions. We used an RCI setup (Stoupin et al, 2016;Pradhan et al, 2020) on the X-ray optics testing beamline 1BM (Macrander et al, 2016) at the Advanced Photon Source (APS), shown schematically in Fig. 8.…”

Diamond Channel-Cut Crystals for High-Heat-Load, Beam-Multiplexing, Narrow-Band X-ray Monochromators

“…Apparently, laser machining is accompanied by graphitization of the diamond surface. To erase the blackening, we anneal the crystals in air at a temperature of 630-650 • C for 3 hours, as in our previous and recent studies [28,42]. After annealing, the blackening has vanished, as seen on the photographs in Figs.…”

“…In this technique, Bragg reflection images of a crystal under study are measured with a pixel x-ray detector, with images being taken sequentially at different incidence angles to the reflecting atomic planes of the wellcollimated x-rays; Bragg reflection maps are calculated for the reflection peak intensities, angular widths and angular positions. We used an RCI setup [42,44] at xray optics testing beamline 1BM [45] at the Advanced Photon Source (APS), schematically shown in Fig. 8.…”