Structure of nanoparticles from powder diffraction data using the pair distribution function

The local structure of nanoparticles can be determined by a direct interpretation of the first peaks observed in the radial distribution function obtained from powder diffraction data measured to high Q values. Single peak fits to these maxima yield the mean distances and width of the distribution in the first few neighbouring shells. An algorithm is presented to calculate the radial distribution function based on the simulation of a single nanoparticle. This algorithm allows a flexible description of nanoparticle size and shape. Based on this algorithm the structure of CdS:glutathione nanoparticles of less than 2 nm diameter is presented. This structure consists of a US core with tetrahedrally coordinated first neighbours and a shell of glutathione molecules. Within the core several stacking faults lie in different orientations with a stacking fault probability of 40%.