Abstract

FERNANDO-MARQUEZ, C.; MONDRAGON-GALICIA, G.; BAZAN-DIAZ, L.  and  REYES-GASGA, J.. Particle size and convergent electron diffraction patterns of triangular prismatic gold nanoparticles. Rev. mex. fis. [online]. 2021, vol.67, n.4, e041005.  Epub Mar 14, 2022. ISSN 0035-001X.  https://doi.org/10.31349/revmexfis.67.041005.

Convergent beam diffraction (CBED) patterns of nanoparticles are possible. CBED of triangular prismatic shaped gold (Au) nanoparticle with focus on diffraction pattern symmetry and forbidden reflections observed along [111] and [112] zone axes are reported in this work. It is well known that the CBED patterns of nanoparticles of 30 nm or less in size only show bright kinematical discs. The dynamic contrast with Kikuchi and sharp HOLZ lines within the bright discs, as observed in CBED of volumetric materials, is well observed in particles larger of 500 nm in size. In addition, it is shown that the 1/3[422] and 1/2[311] weak forbidden reflections observed in the [111] and [112] electron diffraction patterns of these particles do not modify the symmetry of the CBED patterns, but they disappear as the size of the particle increases. The symmetry of the CBED patterns are always observed in concordance with the space group Fm3m (No. 225) of the Au unit cell. The possible explanations for observing forbidden reflections are the incomplete ABC stacking due to surface termination and the stacking faults in the fcc structure.

Keywords : Gold nanoparticles; crystal morphology; characterization; transmission electron microscopy; converging beam electron diffraction; electron diffraction.