Structural Analysis of Ligand-Protected Smaller MetallicNanocrystals by Atomic Pair Distribution Function under PrecessionElectron Diffraction

Atomic pair distribution function (PDF) analysis has been widely used to investigate nanocrystalline and structurally disordered materials. Experimental PDFs retrieved from electron diffraction (ePDF) in transmission electron microscopy (TEM) represent an attractive alternative to traditional PDF obtained from synchrotron X-ray sources, particularly for studying minute samples. Nonetheless, the inelastic scattering produced by the large dynamical effects of electron diffraction may obscure the interpretation of ePDF. In the present work, precession electron diffraction (PED-TEM) has been employed to obtain the ePDF of two different samples ––lipoic acid- and hexanethiol-capped gold nanoparticles (~ 4.5 nm and 4.2 nm, respectively)¬¬–– randomly oriented and measured at both liquid-nitrogen and room temperatures. The electron diffraction data were processed to obtain ePDFs which were subsequently compared with PDF of different ideal structure-models. The results demonstrate that the PED-ePDF data is sensiti...