Messung der elastischen und inelastischen Streuanteile im Bereich der Bragg‐Reflexe eines Pentaerythrit‐Einkristalls mit Hilfe von Mössbauer‐Quelle und ‐Absorber

Measurements of thermal diffuse scattering (TDS) based on a Mössbauer diffraction method are given for 11 Bragg reflexions of pentaerythritol. The experimental values are in a good agreement with the Debye–Waller–Faxén theory provided that the elastic constants of pentaerythritol reported by Haussühl [private communication (1976)] are used and not those of Srivastava [ Acta Cryst. (1962). 15 , 1306]. This demonstrates the validity of the Debye–Waller–Faxén theory for a molecular crystal of non‐cubic symmetry. The influence of phonon dispersion, two‐phonon scattering, instrumental broadening, extinction and elastic anisotropy is discussed. A simple experimental TDS correction for X‐ray Bragg intensities is suggested.