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

Abstract

Scanning tunneling microscopy/spectroscopy (STM/STS) at 4.8 K has been used to examine the growth of a double-decker bis(phthalocyaninato)yttrium (YPc 2 ) molecule on a reconstructed Au(111) substrate. Local differential conductance spectra (dI/dV ) of a single YPc 2 molecule allow the characteristics of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) to be identified. Furthermore, lateral distributions of the local density of states (LDOS) have also been obtained by d I/dV mapping and confirmed by first principles simulations. These electronic feature mappings and theoretical calculations provide a basis for understanding the unique STM morphology of YPc 2 , which is usually imaged as an eight-lobed structure. In addition, we demonstrate that bias-dependent STM morphologies and simultaneous d I/dV maps can provide a way of understanding the stability of two-dimensional YPc 2 films.

Surface chemistry of porphyrins and phthalocyanines

“…A similar lattice structure and a 451 azimuthal rotation angle between the two ligands were reported for DyPc 2 on a Pb (1 1 1) film [223]. Other examples for MPc 2 complexes include TbPc 2 on Cu(1 1 1) [224,225], LuPc 2 on Ag(1 1 1) [226], DyPc 2 on Au(1 1 1) [221,227] and YPc 2 on Au(1 1 1) [228,229]. Heteroleptic double-decker complexes of the type MPcNc with one phthalocyanine (Pc) and one naphthalocyanine (Nc) ligand (cf.…”

Low-temperature scanning tunneling microscopy study on the electronic properties of a double-decker DyPc2molecule at the surface

“…Scanning tunneling microscopy (STM) is a powerful tool to probe the electronic and magnetic properties of the adsorbed molecules due to its sub-molecular imaging resolution and ability to sense the local electronic properties of low-dimensional systems as well. In recent years, a great number of studies have employed the STM technique to explore the self-assembling behavior, [20][21][22][23] electronic structures [24][25][26] and spin states [27][28][29] of the double-decker LnPc 2 molecules under ultrahigh vacuum conditions. However, the 4f electron states, which are responsible for the large magnetic moment of the molecular magnets, might be spatially localized around the nuclei and hence barely contribute to the tunneling current, causing the 4f electrons to become elusive to STM measurements.…”

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

“…Nevertheless, a desorption or lateral displacement of the upper porphyrin is possible, which is in agreement with a recent report. [24] It is important to note that the manipulation procedures were performed at 6 K, where thermal motions are frozen. It is plausible to assume that the demonstrated rotational rearrangements occur spontaneously at elevated temperatures, where the rotation barrier given by intramolecular interactions can be overcome.…”