Linearly graded GeSi beam-expanding/compressing X-ray monochromator

In standard single-crystal V-channel germanium (220) X-ray beam-expanding/compressing monochromators for Cu Kα₁ radiation, a total beam expansion/compression of 5 and 10 corresponding to the asymmetry angles of 9 and 12° is achieved, respectively. Higher one-dimensional beam expansion/compression is achievable using larger angles of asymmetry at the expense of a decrease in the total intensity. To increase the intensity, a linearly graded Ge-rich Ge_xSi_1−x single crystal was used to prepare a monochromator with 15° asymmetry angles (total expansion/compression factor of 21) for Cu Kα₁ radiation. The X-ray diffraction measurements show more than three times higher peak intensity at the output compared with that of a pure Ge monochromator.