Structures of Self-Assembled n-Alkanethiols on Gold by Reflection High-Energy Electron Diffraction

<div>TThe structures of long-chain alkanethiols (C₁₈H₃₇SH) chemisorbed on an Au(111) single crystal were investigated using reflection high-energy electron diffraction (RHEED). The primary (√3x√3)R30° structure observed as a major species in the as-deposited films contains gold adatoms below the sulfur headgroups. Between the small ordered domains with the alkyl chains tilting toward six directions are azimuthally disorderly packed regions, with a similar average tilt of 30.2°. In contrast, a significant reduction in the coverage of gold adatoms is found in the thermally-induced (2√3x3)_rect phase. This superlattice is shown to contain a mixture of two sulfur arrangements, both of which exhibit a small S‒S distance, and the pairing of the aliphatic chains. A microscopic picture is then given for the structural transition. These findings demonstrate how the RHEED technique may be used to resolve structures of nanometer-thick thin films with multiple orders at the interfaces.</div>

Structures of Self-Assembled n-Alkanethiols on Gold by Reflection High-Energy Electron Diffraction

<div>TThe structures of long-chain alkanethiols (C₁₈H₃₇SH) chemisorbed on an Au(111) single crystal were investigated using reflection high-energy electron diffraction (RHEED). The primary (√3x√3)R30° structure observed as a major species in the as-deposited films contains gold adatoms below the sulfur headgroups. Between the small ordered domains with the alkyl chains tilting toward six directions are azimuthally disorderly packed regions, with a similar average tilt of 30.2°. In contrast, a significant reduction in the coverage of gold adatoms is found in the thermally-induced (2√3x3)_rect phase. This superlattice is shown to contain a mixture of two sulfur arrangements, both of which exhibit a small S‒S distance, and the pairing of the aliphatic chains. A microscopic picture is then given for the structural transition. These findings demonstrate how the RHEED technique may be used to resolve structures of nanometer-thick thin films with multiple orders at the interfaces.</div>

Supramolecular chemistry based on 4-acetylbiphenyl on Au(111)

On a gold surface, supramolecules composed of 4-acetylbiphenyl molecules show structural directionality, reproducibility and robustness to external perturbations, with gold adatoms serving as stabilizing agents.

Thermally induced intra-molecular transformation and metalation of free-base porphyrin on Au(111) surface steered by surface confinement and ad-atoms

We investigated chemical transformations of a fluorinated free-base porphyrin, 5,10,15,20-tetrakis(4-fluorophenyl)-21,23H-porphyrin under a Au(111) surface confinement and including gold adatoms by using an experiment and DFT calculations.

Direct on-surface synthesis of gold–phthalocyanine via cyclization of cyano-groups with gold adatoms

Au–(dibenzo[fg,op]tetracene) porphyrazine has been synthesized on an Au(111) surface by using the precursor of dibenzo[fg,op]tetracene-5,6,12,13-tetracarbonitrile via cyclization of cyanogroups with Au adatoms.

Gold adatoms modulate sulfur adsorption on gold

Sulfur adsorption on Au(111) at high coverage has been studied by density functional calculations.