On the effect of the electron shell structure of the atoms in x-ray diffraction*

Publisher Website
Google Scholar
Abstract
The analytical representation of the atomic scattering amplitudes allows the study of the effect of the different electron shells of atoms in x-ray diffraction. The K and L components can be readily recognized. A method is proposed to separate both components from the observed amplitudes. With this method it is possible to calculate the Patterson and Fourier maps of the K and L electrons of a crystal. The K -electrons Patterson map is a natural sharpened Patterson very similar to the difference temperature Patterson. It is shown that the K -electrons density map corresponds to isolated atoms, the continuous molecular electronic cloud disappearing. The K - and L -electrons density maps can be obtained independently. These maps are specially interesting in the study of the charge-density distribution in a molecule. It is shown that the method currently used for determining the thermal tensor of the atoms can give erroneous values, because the reflections of high θ values include the contribution of the K electrons alone, but the remaining reflections are affected by the contribution of both K -and L -electron shells. The method can be used in the analysis of complicated structures.