Stoichiometric and ultra-stable nanoparticles of II-VI compound semiconductors

Nanoparticles of (CdSe)_n are found extremely stable at n = 33 and 34 with structures distinctively different from the bulk fragments. They grow exclusively in large amount with a simple solution method. The diameter is determined as 1.5 nm. Such ultra-stable nanoparticles had been predicted both theoretically and experimentally after the discovery of carbon fullerenes, but not been produced macroscopically in any other element or compound system. First-principles calculations predict that the structures of (CdSe)₃₃ and (CdSe)₃₄ are puckered (CdSe)₂₈-cages accommodating respectively (CdSe)₅ an (CdSe)₆ inside to form a three-dimensional network of essentially hetero-polar sp³-bonding.