Carbon ad-dimer interactions with nanocarbons as a route to new materials

Peter Zapol1, Michael Sternberg2, L. A. Curtiss, curtiss@anl.gov1, D. M. Gruen2,
Gary S. Kedziora, gary.kedziora@wpafb.af.mil3, David A. Horner, dah@noctrl.edu4,
and Paul C Redfern, redfern@anchim.chm.anl.gov5. (1) Materials Science and
Chemistry Divisions, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL
60439, (2) Materials Science Division, Argonne National Laboratory, 9700 S. Cass
Ave., Argonne, IL 60439, (3) User Productivity Enhancement and Technology
Transfer, High Performance Technonogies, Inc, ASC/HP Bldg. 676, 2435 5th St.,
Wright Patterson Air Force Base, OH 45433-7802, (4) Department of Chemistry,
North Central College, 30 N. Brainard St., Naperville, IL 60540, (5) Chemistry
Division, Argonne National Laboratory, Argonne National Laboratory, 9700 S. Cass
Ave., Argonne, 60439

The adsorption of carbon dimers on diamond surfaces results in the growth of
ultrananocrystalline diamond films. We have investigated mechanisms of growth
and secondary nucleation of diamond crystallites on several diamond surfaces
using DFTB. The adsorption of carbon dimers on carbon nanotubes leads to a rich
spectrum of structures and electronic structure modifications. Barriers for the
formation of carbon dimer induced defects calculated using DFTB are considerably
lower than those for the Stone-Wales defect. The electronic states of the
ad-dimers depend on defect structure and tube type and size. Multiple adsorption
of carbon dimers provides a route to structural engineering of patterned tubes
that may be of interest for nanoelectronics.