A Low-Temperature Scanning Tunneling Microscope Investigation of a Nonplanar Dysprosium−Phthalocyanine Adsorption on Au(111)

Abstract

Self-assemblies of a nonplanar dysprosium−phthalocyanine (DyPc) molecule on the reconstructed Au(111) substrate have been examined with a low-temperature scanning tunneling microscope (STM). A four-lobed structure with a dark center hole is imaged as an isolated DyPc molecule, where the Dy atom is expected to be positioned below the Pc plane and bound to the Au substrate. Careful measurements reveal that the axes of isolated DyPc molecules align well with the high symmetry directions of Au. This fact illustrates a strong molecule−substrate interaction. In a monolayer film, a square molecule lattice is observed, where the geometries of the molecules can be determined by our submolecularly resolved STM images. The deduced lattice vectors and the azimuthal angles of the molecules account for a dominant molecule−molecule interaction. In a bilayer growth regime, the bonding configurations of the molecules in the second layer coincide with that of the first layer. A similar azimuthal angle appearing in the two layers may indicate a columnar packing geometry of DyPc molecules.

Metal-free phthalocyanine (H2Pc) molecule adsorbed on the Au(111) surface: formation of a wide domain along a single lattice direction

“…Scanning tunneling microscopy (STM) has played an important role in the characterization of Pc films [6]. However, STM can only reveal the topmost surface, and the direct information of the interface cannot be obtained with this technique [7][8][9][10]. In studying the adsorption of the double-layer molecules, it might be necessary to compare the results with those obtained on metal-free Pc, as the bottom Pc layer does not contain a metal atom.…”

The Frontier of Molecular Spintronics Based on Multiple-Decker Phthalocyaninato TbIIISingle-Molecule Magnets

“…Au (111) and Ag(111) surfaces, which were cleaned in ultra-high vacuum (UHV) chambers prior to the molecular deposition, were used as substrates. [69,70] For the STM/STS experiments, the sample was kept at a T of $4.7 K. The dI/dV spectra were obtained using a lock-in amplifier with a modulation voltage of 4 mV (1 mV) superimposed onto the tunneling bias voltage for wide-range (near the Fermi level) STS measurements. [71,72] Studying the films at cryogenic temperatures improves the STM capabilities for molecular characterization for a variety of reasons.…”

Multiple-decker phthalocyaninato Tb(III) single-molecule magnets and Y(III) complexes for next generation devices

“…We were motivated to investigate the unique electrical and magnetic properties of metal-Pc SMMs by directly accessing isolated molecules on a Au surface via STM and STS and to investigate the bulk phase electron transport properties for next generation devices [89,[131][132][133][134]. These aspects are discussed in the following sections.…”

“…We investigated the characteristics of LnPc 2 and LnPc (Ln 3+ = Tb, Dy, and Y) deposited on a Au(1 1 1) surface [131][132][133][134]. Both complexes were shown to coexist on the Au(1 1 1) surface on the basis of height profiles, X-ray photoelectron spectroscopy (XPS), and dI/dV mapping.…”

“…We studied double-decker LnPc 2 (Ln 3+ = Tb, Dy, and Y) molecules adsorbed on Au(1 1 1) at 4.7 K by using STM [131][132][133][134]. LnPc 2 molecules can be adsorbed onto a surface by thermal evaporation, and the morphology of LnPc 2 on Au(1 1 1) varied from individual molecules to 2D thin films.…”