Surface properties of CdSe nanocrystals. Panels (A) and (B) depict transmission electron micrographs of quasi-spherical quantum dots with two orientations on the substrate, and panel (C) depicts a quantum rod.11 All scale bars are 5 nm. In the atomic models, the crystalline orientations and lattice facets are identified by their Wurtzite (WZ) Miller indices, and the polarity of each facet is noted as Cd2+ for cationic, Se2− for anionic, and CdSe for nonpolar. Panel (D) illustrates the terminal dangling orbitals on each type of facet, and panel (E) shows the effects of surface hole traps on the fluorescence of small 2.1 nm nanocrystals.