A neutron diffraction study of potassium dihydrogen phosphate by Fourier synthesis

Projections of the distribution of atomic nuclei in potassium dihydrogen phosphate at room temperature have been obtained by Fourier synthesis of single-crystal neutron diffraction data. Series termination effects have been examined and corrected for, either by specific assessment of the diffraction rings or by difference syntheses. The parameters so obtained are confirmed by least-squares analyses and give a reliability index of 7%. Hydrogen peaks occur midway between two oxygen atoms and appear circular when viewed along the O—H—O bond, but elliptical when viewed across it. The PO4 tetrahedra are much more nearly regular than previously supposed, and the O—H—O bonds are inclined at not more than ½º to the xy-plane.