The low-angle atomic scattering factors and charge density of zinc

Abstract

The 0002 and low-angle X-ray atomic scattering (form) factors of zinc have been accurately measured by the systematic critical voltage (V _c) method in high-energy electron diffraction. An indication of the value of the form factor was also obtained by this technique. These results are in good agreement with recent X-ray Pendellosung data for this element and charge difference maps based on this information indicate that bonding in zinc is achieved by the asymmetric depletion of electrons from atomic sites in 〈210〉 directions and redistribution such that there is a maximum build-up of charge density around the mid-point between third nearest-neighbour atoms in the basal plane. This charge distribution is entirely consistent with the long c/a of zinc (1·856), and a comparison with the equivalent charge densities for beryllium (c/a = 1·58) suggest that there is a simple correlation between bonding mechanism and c/a ratio for these hexagonal elements.