3D structures of colloidal nanoparticles typically deviate from the lattice structures measured and expected in their bulk counterparts. This is presumably because of the dominance of surface dangling bonds, defects, and dislocations within the volume of individual nanoparticles. Indeed, such structural uniqueness determines physical, chemical, and optical properties of colloidal nanoparticles in many applications. To understand unique structural features of colloidal nanoparticles, especially when they are smaller than a few nanometers, a method that can precisely determine the positions of the individual constituent atoms is required. We introduce our experimental efforts that combine new techniques including high-resolution graphene liquid cell TEM, structure reconstruction algorithm, and atomic structure identification. We apply this development to determine the 3D atomic arrangements of metallic nanoparticles in solution. Our high-resolution 3D density maps and fitted atomic models show crystal structures of individual particles with structural degeneracies, including single crystalline, polycrystalline, distorted structures, and a dislocation. We also discuss the extent of this new analytical method regarding types and dimensions of materials systems which require unprecedented structural information in native conditions.

3D atomic structures of colloidal nanoparticles by “one-particle Brownian reconstruction” based on liquid phase TEM

ACS Fall 2020 Virtual Meeting

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