The adsorption and reaction of acetic acid (CH3COOH) on the Si(001) surface are investigated by first-principles density-functional calculations within the generalized gradient approximation. We consider the two different reaction pathways that result in formation of the dissociative configuration and the di-σ configuration. The dissociative configuration involving the O H bond cleavage is formed via a precursor where the hydroxyl oxygen is attracted to the down atom of the Si dimer. On the other hand, the attraction of the carbonyl oxygen to the down Si atom leads to formation of the di-σ configuration where the π bond in the double C O bond is broken to form two new σ bonds with the Si dimer. Based on our results for the energy-profiles of the two reaction pathways, we predict that at room temperature the desorption of CH3COOH from the di-σ configuration is thermally activated, while such a thermal desorption from the dissociative configuration is not probable because of its large adsorption energy.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 2005 Nov 15|