Azimuthal dependence of the quadrupole resonances in sodium nitroprusside investigated by Moessbauer γ-ray diffraction

The ratio of quadrupole resonances in sodium nitroprusside was determined from diffracted beam Moessbauer spectra taken as a function of the azimuthal rotation of single crystals around the Fourier vector Kh. The experiments were performed with h=(022) and (055) using a Moessbauer γ-diffractometer. The data are sensitive to the orientation of the electric field gradient tensor, which was also deduced from X-ray data for comparison. (orig.)