End-On and Side-On Bonding of Ketones to Surfaces: Acetone on the Ru(001) and Pt(111) Surfaces

High-resolution electron-energy-loss spectroscopy has verified the existence of two fundamentally different types of adsorbed acetone, ${\eta }^1$-bonded acetone on Pt(111) and ${\eta }^2$-bonded acetone on Ru(001). On a Ru(001) surface, the Lewis acidity of which has been increased by the presence of oxygen adatoms, the ${\eta }^1$ and ${\eta }^2$ forms of acetone coexist. The ${\eta }^1$-bonded acetone desorbs molecularly, whereas ${\eta }^2$-bonded acetone is a precursor to dissociation on the surface.