DETERMINATION OF THERMAL DIFFUSE SCATTERING IN A SILICON CRYSTAL BY MEANS OF MOSSBAUER EFFECT

The 14.4 keV (λ=0.8602 Å)γ-rays from a57Co source were scattered by the (444) and (555) planes of a perfect silicon crystal and the inelastic contribution to the total scattering was determined by means of the Mössbauer effect. It was found that the thermal diffuse scattering has intensity maxima under the Bragg peak, as expected on the basis of the lattice wave theory of the X-ray diffuse scattering. The ratio between the integrated intensities of the thermal diffuse and the total scatterings was equal to 0.47 and 0.55 for the (444) and (555) reflections respectively, the geometry of the experiment being similar to those commonly used for studies of diffuse scattering. The integrated Bragg intensities of the above reflections were compared with those calculated by using the formulae of the dynamical theory of diffraction. A comparison was also made between the intensities of the thermal scattering at the Bragg angle and those calculated by using some simplifying assumptions for the numerical evaluation of the formulae of the theory. A satisfactory agreement between experimental and calculated values was found for both the Bragg and the thermal diffuse scatterings. © 1969 Società Italiana di Fisica.