Effect of surface reconstruction on molecular chemisorption:: A scanning tunneling microscopy study of H8Si8O12 clusters on Au(111) 23x√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) 23xroot3 surface. All three experimental techniques independently support desorption of approximately 10-15% of the HsSi(8)O(12) 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 x root3 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(1 11) 23 x 0 reconstructed surface. The preferential cluster adsorption/desorption behavior creates a unique pattern of holes and channels in the Au/H7Si8O12 adsorbate layer surface.