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.

• Received 10 February 1983

DOI:https://doi.org/10.1103/PhysRevLett.51.682