Observation of dynamical effects in Bragg-Bragg high-resolution multiple diffraction

An X-ray optical layout is demonstrated that permits high-resolution multiple diffraction experiments with two-dimensional collimation. Although the use of synchrotron radiation is still desirable, the layout described allows preparatory measurements to be made with the use of a conventional X-ray tube. The collimation of the incident beam of 15 × 12 arc sec was achieved with the use of two symmetrically cut Ge(111) crystal. The applicability of the layout was first tested by observing multiple-diffraction reflection curves in the (000)(111)(220) configuration for an ideal symmetrically cut Ge(111) crystal. The layout allowed the observation, for the first time, of a multiple-diffraction “pumping” effect on InGaP/GaAs(111) heteroepitaxial structures. The thickness sensitivity of the pumping effect was demonstrated.