Control of Reaction Pathway and the Nanostructure of Final Products through the Design of Modulated Elemental Reactants

This review focuses on the use of designed reactants, consisting of ultrathin elemental layers sequentially deposited in ultrahigh vacuum, to control reaction pathways and the structure of compounds formed. Two reaction pathways are discussed. The first uses controlled nucleation of an amorphous intermediate to kinetically access compounds under conditions where they may be thermodynamically unstable. The second approach takes advantage of the controlled diffusion lengths in elementally modulated reactants and slow diffusion rates at low temperatures to prepare superlattice and heterostructure compounds with controlled composition and structure.