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Migration of various important species (H, CH3, CH2, C2H, and C2H2) on a diamond (111) surface has been investigated theoretically, using a cluster approach and the second-order Møller-Plesset perturbation theory. The order of the energies (barriers) obtained for a single jump between two neighboring radical sites is CH2<H<C2H≈CH3 (52, 248, 350, and 353 kJ/mol, respectively). The C2H2 species is assumed to migrate by an alternating onefold and difold site adsorption to the surface. The corresponding barrier obtained for C2H2 is 186 kJ/mol, which is somewhere in between that of CH2 and H. The present type of surface migration of chemisorbed species will, with one exception, be energetically favorable in comparison to any desorption process. In the case of C2H2, a desorption process will be energetically favorable.