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 H8Si8O12 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.