High energy x-ray diffraction on ultrasound excited crystals (English shop)

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The thesis “High Energy X-Ray Diffraction On Ultrasound Excited Crystals” deals with time-resolved and time-integrated high-energy X-ray diffraction on ultrasound-excited silicon crystals. Using high-energy synchrotron radiation with an energy above 80 keV and a high-resolution triple-axis diffractometer with a maximum angular resolution of 0.01 arcseconds, ultrasound-induced satellite reflections from the bulk of a crystal are detected for the first time in Laue scattering geometry. It is shown which propagation direction and amplitude the waves excited by a transducer in the high-frequency range assume within the crystal. High-resolution two-dimensional scans of the diffraction plane contribute substantially to clarifying the propagation direction. The angular positions of the measured satellite reflections are confirmed theoretically. In order to describe the time-dependent intensity profiles, a simulation program based on dynamical diffraction theory has been developed, which allows time-integrated and time-resolved rocking curves of different crystal reflections to be calculated as a function of the energy of the diffracted radiation, the ultrasound frequency and the ultrasound amplitude. Since the extinction lengths of the satellite reflections can be driven beyond the crystal thicknesses by the ultrasound waves, they change their diffraction intensity periodically, which is demonstrated by time-resolved measurements of the X-ray diffraction intensity with a resolution of 200 ps.