Structure Identification of Two-Dimensional Colloidal Semiconductor Nanocrystals with Atomic Flat Basal Planes.

Discrete nature of thickness and flat basal planes of two-dimensional (2D) nanostructures display unique diffraction features. Their origin was uncovered by a new analysis method of powder X-ray diffraction, which reveals thickness and lattice orientation of the 2D nanostructures. Results indicate necessity of adoption of a different unit cell from the corresponding bulk crystal with the same internal atomic packing. For CdSe 2D nanostructures with zinc blende atomic packing, pseudotetragonal lattices are adequate, instead of face-centered cubic.