The adsorption of CO on Au(1 1 1) at elevated pressures studied by STM, RAIRS and DFT calculations

The adsorption of carbon monoxide on the Au(1 1 1) single-crystal surface has been investigated in the [10 −3–10 3 Torr] range at room temperature (RT). Using scanning tunneling microscopy (STM), a CO-induced modification of the surface morphology (step edge roughening) and terrace structure (22×√3→1×1 transition) is evidenced. Reflection absorption infrared spectroscopy (RAIRS) experiments suggest that CO molecules are linearly chemisorbed on top of gold atoms and that adsorption occurs only above ∼1 Torr CO pressure at RT. Density functional theory (DFT) calculations, through consideration of perfect, stepped or kinked surfaces support these results and give additional evidence of strong structure sensitivity for CO adsorption on gold.