Acetone on silicon (001): ambiphilic molecule meets ambiphilic surface

Abstract

Using density functional theory, we report detailed reaction path calculations for the reaction of acetone with the silicon (001) surface. We identify the key reaction intermediates of dissociative adsorption and the transition states between them. This resolves the identity of the one-dimer intermediate observed in STM experiments and its role in the formation of several two-dimer-wide end products of dissociation. Key to the understanding of the dissociation mechanism is the ambiphilic character of the two reactants, that is the simultaneous expression of electrophilic and nucleophilic reactivities in both the surface and the acetone molecule.

Acetic acid on silicon (001): An exercise in chemical analogy

“…The only kinetic holdup occurs for some acetone molecules that are diverted into another reaction channel (not shown here) leading to a metastable [2 + 2] cycloaddition product. 12,[26][27][28][29][30] We postulate here that the dimer-centered feature observed by Shimomura et al 6 for acetic acid is formed by a chemically analogous pathway. This path is shown in Fig.…”

“…Energies of adsorption and activation energies are calculated using a procedure that we refer to as a cluster compound model, 12,13 which has a solid track record 14,15 of describing processes of molecular dissociation on the Si(001) surface. This approach provides a good estimate of hybrid-DFT (B3LYP; Ref.…”

“…The full details of this approach as deployed here for the Si(001) surface are given in Ref. 12. For the Ge(001) surface, we use exactly the same approach except that four-dimer Ge 53 H 44 and two-dimer Ge 15 H 16 clusters are used in place of the silicon clusters.…”

“…(Color online) Schematic valence structure diagrams outlining (a) the reaction channel for acetone on Si(001) that leads in four steps to the dimer-bridge dissociated structure ac-D4 (see Ref 12. for details), and (b) the chemically analogous path for acetic acid on Si(001).…”

Orientation and stability of a bi-functional aromatic organic molecular adsorbate on silicon

“…Determining the adsorption structures of organic molecules on the technologically important Si(001) surface is an important fundamental step toward this goal. [5][6][7][8][9][10][11][12][13][14] Recent advances in atomic-scale imaging, photoelectron and X-ray absorption spectroscopy, and theoretical calculations now provide us with the ability to determine the structure of surface adsorbates with atomic-scale precision. Scanning tunnelling microscopy (STM) can provide atomically-resolved images of individual adsorbates, often resolving key features that are critical to the correct identification of the structures.…”