Powder diffraction beyond the Bragg law: study of palladium nanocrystals

Quantitative measurements of the peak shift, intensity and peak width of palladium nanoclusters on modifying the gaseous environment, e.g. chemisorption of oxygen, are presented. A detailed model for a palladium catalyst strongly suggests a significant contribution from icosahedral clusters that do not transform into the (beta)-hydride phase under hydrogen.