Low-Temperature Scanning Tunneling Microscopy Investigation of Bis(phthalocyaninato)yttrium Growth on Au(111): From Individual Molecules to Two-Dimensional Domains

Abstract

We show a 4.8 K STM observation of a double-decker bis(phthalocyaninato)yttrium (YPc 2 ; Pc ) phthalocyanine) molecule adsorption on Au(111) substrate. An eight-lobed structure was imaged as the submolecule STM contrast of a single molecule both in an isolated state and in a molecule film. This feature arises from the top Pc group, where both sides of the four phenyl rings are highlighted. As an isolated molecule, the adsorption orientation is determined by the lower Pc, the diagonal axis of which aligns parallel to the close-packed direction of Au(111). In a 2D film, a near-square molecule lattice appears with a unit of ∼1.47 × 1.38 nm 2 , and one of the lattice vectors is rotated by ∼15°from the close-packed direction. A tentative model is provided to illustrate the molecule array where neighboring molecules are rotated by ∼30°from each other. In this way, the lower Pcs should align along the [101 j ] and [2 j 11] directions (or their equivalent directions) alternately. All these facts illustrate the molecule-substrate and the molecule-molecule interactions in the initial adsorption and in the film accumulation.

Bis(phthalocyaninato)yttrium grown on Au(111): Electronic structure of a single molecule and the stability of two-dimensional films investigated by scanning tunneling microscopy/spectroscopy at 4.8 K

“…1(a)) and 2-D islands develop at high coverage ( Fig. 1(b)) [24]. In addition, square islands usually dominate on the elbow sites of the herringbone reconstructions of Au, and these sites have been shown to be the nucleation sites of metal atoms and organic molecules.…”

“…Its growth behavior on Au(111) has already been reported elsewhere [24]. Here, we try to explore the electronic structure of a single molecule and the stability of YPc 2 films.…”

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.…”

Assembly and Manipulation of Rotatable Cerium Porphyrinato Sandwich Complexes on a Surface

“…[11,12] These large double-and triple-decker molecules are generally susceptible to thermal decomposition and often unsuitable for high-temperature vapor deposition, indeed, only a few examples are reported. [13,14] Alternatively, observations are possible at solid/liquid interfaces in an insulating organic solvent [12,15] or under electrochemical control in an electrolyte solution. [16] Herein we report a novel route for the synthesis of bis(porphyrinato)cerium double-decker complexes (Ce-(TPP) 2 , TPP = tetraphenylporphyrin; Figure 1 a, c) directly on a Ag(111) surface under ultra-high-vacuum conditions by exposing a porphyrin precursor layer to an atomic beam of Ce followed by a temperature-programmed reaction and desorption of surplus material.…”