Diffraction peaks corresponding to diffraction lines in photographic observations were found in high-angular-resolution diffractometry of the 220 thermal diffuse spot of a germanium single crystal in the Laue arrangement. The experiment was performed by means of monochromatized synchrotron radiation and a triple-crystal diffractometer with a collimator and an analyzer of grooved silicon crystals. Agreement between experimental peak profiles and calculations based on dynamical diffraction theory gives decisive evidence of anomalous transmission of x rays scattered by phonons for the first time.

• Received 15 August 1988

DOI:https://doi.org/10.1103/PhysRevLett.62.925