Ni(II) porphine nanolines grown on a Ag(111) surface at room temperature

Abstract

The room temperature growth and ordering of (porphyrinato)nickel(II) (or nickel(II) porphine, NiP) molecules on the Ag(111) surface have been investigated using scanning tunnelling microscopy (STM) and low-energy electron diffraction (LEED). Results obtained at one monolayer (ML) coverage indicate a well-ordered molecular layer in which the porphyrin molecules have a flat orientation with the molecular plane lying parallel to the substrate and forming a hexagonal overlayer on the surface. LEED data obtained from one monolayer of the NiP on the Ag(111) surface show the formation of two mirror domains each rotated either clockwise or counterclockwise by 6º with respect to the substrate. NiP molecules forming a second layer self-assemble at room temperature into well-ordered and uniformly separated nanolines. These nanolines consist of hexagonally ordered NiP molecules and are found to be 1 to 4 molecules wide depending on molecular coverage. The completed second monolayer preserves the same planarity and hexagonal ordering as the first molecular layer but with a 4% lateral relaxation which produces a periodic modulation of approximately 5 nm.