Propanoate grafting on (H,OH)-Si(0 0 1)-2 × 1.

We have examined the reactivity of water-covered Si(0 0 1)-2 × 1, (H,OH)-Si(0 0 1)-2 × 1, with propanoic (C2H5COOH) acid at room temperature. Using a combination of spectroscopic techniques probing the electronic structure (XPS, NEXAFS) and the vibrational spectrum (HREELS), we have proved that the acid is chemisorbed on the surface as a propanoate. Once the molecule is chemisorbed, the strong perturbation of the electronic structure of the hydroxyls, and of their vibrational spectrum, suggests that the molecule makes hydrogen bonds with the surrounding hydroxyls.