Fragmentation pathways of acetic acid upon adsorption on Si(1 0 0)2 × 1

The reaction of acetic acid on the Si(1 0 0)2 × 1 surface has been investigated by density functional calculations on a two-dimers cluster model. We found that, once in the physisorbed state, acetic acid can proceed to react via two different pathways. In the first one, the cleavage of the hydroxylic bond is followed by a number of migrations of the dissociated hydrogen as well as structural rearrangements that eventually lead to the incorporation of an oxygen atom into the silicon surface, with a Si-O-Si structure. The second reaction pathway involves an initial C-H bond breakage, and evolves into a C-C bond cleavage and binding of the separate methyl and carboxylic fragments on top of a silicon dimer.