Surface spectroscopic study of the stabilization mechanism for shape-selectively synthesized nanostructured transition metal colloids

Nanoscale palladium and nickel colloids prepared in the presence of certain tetra-n-octylammonium carboxylates contain a high proportion of nonequilib rium trigonal cross section particles. Specifically, those carboxylates whi ch bear a hydroxy function at the a-position, e.g., tetra-n-octylammonium g lycolate, exert a strong influence on the shape of the metal colloids. It i s shown by an in situ FTIR study of the preparation of colloidal nickel fro m bis(cyclooctadiene)nickel in the presence of tetra-n-octylammonium glycol ate that the interaction of the alpha-hydroxy carboxylate with the surface of the colloidal metal particle is likely to be the morphology-determining factor in the shape-selective preparation of these metal particles.