Scanning Tunneling Microscopy Observation of Copper-Phthalocyanine and Nucleic Acid Base Molecules on Reduced SrTiO3(100) and Cu(111) Surfaces

Abstract

In order to examine how both adsorbed molecules and underlying substrates affect the appearance of scanning tunneling microscopy (STM) images and the arrangement of the molecules on the surface, copperphthalocyanine (CuPc) and the nucleic acid base molecules are deposited on the chemically active reduced SrTiO₃(100) √5×√5- R26.6° and chemically less active Cu(111) surfaces. STM images of CuPc and the nucleic acid base molecules on SrTiO₃(100) have revealed that the substrate anchors the molecules stably for observation by STM, and each molecule is discriminated according to its shape and size in the image. The molecule of bases adsorbed on the chemically less active Cu(111) surface can diffuse over the surface to self-assemble into novel low-dimensional structures.