title: Propanoate grafting on (H,OH)-Si(0 0 1)-2 × 1.
abstract: 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. As we find evidence that surface hydroxyls are involved in the adsorption reaction, we discuss how a concerted or a radical-mediated reaction (involving the surface silicon dangling bonds) could lead to water elimination and formation of the ester.
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif sur Yvette Cedex, France. Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique, Matière et Rayonnement, 11 rue Pierre et Marie Curie, 75231 Paris Cedex, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bournel
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Gallet
authors.forename: Ulrich
authors.initials: U
authors.lastname: Köhler
authors.forename: Bochra Boughaled
authors.initials: BB
authors.lastname: Ellakhmissi
authors.forename: Stefan
authors.initials: S
authors.lastname: Kubsky
authors.forename: Stéphane
authors.initials: S
authors.lastname: Carniato
authors.forename: François
authors.initials: F
authors.lastname: Rochet