Effect of Surface Reconstruction on Molecular Chemisorption:  A Scanning Tunneling Microscopy Study of H₈Si₈O₁₂ Clusters on Au(111) 23×√3

Abstract

Scanning tunneling microscopy (STM) data are presented in conjunction with reflection-absorption infrared spectroscopy and X-ray photoemission spectroscopy data investigating the adsorbate layer formation of H8Si8O12 clusters on a clean Au(111) 23× 3 surface. All three experimental techniques independently support desorption of approximately 10-15% of the H8Si8O12 clusters from the Au/H7Si8O12 adsorbate layer surface following evacuation of excess H8Si8O12 cluster pressure from the ultrahigh vacuum reaction chamber. Surprisingly, the STM data indicate that unlike all other reported molecular adsorbates having a strong chemical interaction with the Au(111) surface, the 23× 3 surface reconstruction is preserved following chemisorption of H 8Si8O12 clusters. Additionally, at saturation coverage the clusters are preferentially bound to, and predominantly desorb from, specific sites on the Au(111) 23× 3 reconstructed surface. The preferential cluster adsorption/desorption behavior creates a unique pattern of holes and channels in the Au/H7Si8O12 adsorbate layer surface.

Direct Observation of Conformational Changes of β-Substituted Duodecithiophene on a Au(111)-(√3 × 22) Substrate Using in Situ Electrochemical STM in 0.1 M HClO4

“…Interestingly, one domain structure appears to have folded conformations (i.e., ∼180° folding of the oligomer backbone) (Figure ) that are closely packed along the reconstruction rows. A (√3 × 22) unit cell in a reconstructed Au(111) substrate spans approximately 6.3 nm (indicated by a pair of dashed lines in Figure ) along a horizontal covering the 0.5 fcc-bridge-hcp-bridge-0.5 fcc site . The pair of bridging regions contained within the (√3 × 22) unit cell is manifested in the STM image as elevated pairs of parallel stripes.…”

“…As schematically shown in Figure c, the dimensions of the fold are estimated from theoretical calculations to be 2.5 ± 0.1 nm in length (computed from the terminal hexyl carbon of thiophene E to the α terminal carbon of thiophene A) and 1.1 ± 0.1 nm in width (computed from the sulfur of thiophene A to the sulfur of thiophene A′). A (√3 × 22) unit cell spans approximately 6.3 nm along a horizontal covering of the 0.5 fcc-bridge-hcp-bridge-0.5 fcc site . The pair of bridging regions contained within the (√3 × 22) unit cell is manifested in STM images as elevated pairs of parallel stripes.…”

Formation of Mixed Monolayers of Silsesquioxanes and Alkylsilanes on Gold

“…All experiments were performed at room temperature in a set of three custom-built UHV chambers. The chambers and their capabilities have been described previously. − Soft X-ray photoemission spectroscopy was performed at beamline U8B at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. Valence band and Si 2p core level data were obtained with an incident photon energy of 160 eV.…”

Two-Dimensional Polymerization and Reaction at the Solid/Liquid Interface: Scanning Tunneling Microscopy Study

“…The reconstructed surface has a new surface structure different from an ideal crystal surface. 44 There are many kinds of electrodes such as Au, 45,46 Cu, [47][48][49] Pt, 50-52 Si 53 which can generate the reconstruction by using different methods. These methods resulted in the electrode reconstruction at the solid/liquid interface are mainly classified into three aspects: the thermal-induced reconstruction, the potential-induced reconstruction and the absorption-induced reconstruction.…”

“…The reconstructed surface becomes the (fcc)-(bridge)-(hcp)-(bridge)-(fcc) domains with different surface heights. 45 Along the <110> direction of the reconstruction, 23 atoms are compressed and occupied 22 atomic positions, which also lead to the change of the height of the electron. The Au(111) single crystal structure changes from Au(111)-(1 × 1) to Au(111)-(22 × √ -3) and the atomic structure of the solid/liquid interface is also different.…”