Theoretical studies of reactions
on diamond surfaces
This is an abstract
for a talk to be given at the
Fifth
Foresight Conference on Molecular Nanotechnology.
The full article is available at the
author's web site.
Density functional theory and other methods are being used to
examine reactions of tools and other molecules with diamond
surfaces.
In one study, we looked at the interaction of several
mechanosynthesis tools with a pair of radical sites on the
diamond (111) surface. The carbene tool (carbenecyclopropene) is
found to bond preferentially to a single radical site (on top
site) rather than at a bridged site. This means this tool is not
useful for adding a carbon to diamond (111). The C2
tool, on the other hand, is found to add a bridged C2
molecule, through a series of steps which are overall exothermic.
The carbene tool can add a carbon to the bridged C2
molecule, leading to a bridged C3 molecule
perpendicular to the surface, by an overall exothermic series of
steps. If another radical site is activated, the C3
can bend over to a three fold coordinated position, with only a
small barrier. Thus, this series of steps can be used to create a
three fold coordinated C3 molecule on the diamond
(111) surface. These studies are being extended to the
reconstructed diamond (100) surface.
In another study, we are looking at the reaction of H and H2
with the reconstructed diamond(100) surface. We are interested in
barriers to addition, abstraction, and migration.
Finally, we are planning studies (which should be complete by
the time of the meeting) of the reaction of acetylene with the
reconstructed diamond (100) surface.
*Corresponding Address:
Stephen P. Walch, Thermosciences Institute (MS 230-3), NASA Ames
Research Center, Moffett Field, CA 94035-1000, ph: 415-604-6189,
fax: 415-604-0350, email: [email protected]
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