Effect of surface reconstruction on molecular chemisorption: A scanning tunneling microscopy study of H₈Si₈O₁₂ clusters on Au(111) 23 × √3

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.