Dimer reconstruction and electronic surface states on clean and hydrogenated diamond (100) surfaces

Hydroboration of C(100) surface, fullerene, and the sidewalls of single-wall carbon nanotubes with borane

Hydroboration of three allotropes of carbon, i.e., diamond (100) surface, [60]fullerene, and single-wall carbon nanotubes (SWNTs), with borane (BH(3)) has been explored by means of quantum chemical calculations. The calculations predicted that the hydroboration of C(60) and the C(100)-2x1 surface occurs readily, whereas the hydroboration of the sidewall of an armchair (5,5) SWNT is thermoneutral with a barrier height of 11.5 kcal/mol. This suggests that sidewall hydroboration, if viable, would be highly reversible on the (5,5) SWNT. The as-hydroborated carbonous materials can be good starting points for further chemical modification and manipulation of these carbonous materials, given the abundant chemistry of organoboranes.

A DFT study of the 1,3-dipolar cycloadditions on the C(100)-2 x 1 surface

The 1,3-dipolar cycloadditions (1,3-DCs) of a series of 1,3-dipolar molecules onto the C(100)-2 x 1 surface have been investigated by means of hybrid density functional B3LYP method in combination with cluster model approach. It was found that 1,3-DCs on the C(100)-2 x 1 surface are more favorable over their molecular analogues both thermodynamically and kinetically. The enhancement of the reactivity on the surface due to the reduced overlap between the p(pi) orbitals of the surface C=C dimer should be important for the semiconductor industry because it might lead to a breakthrough in the fabrication of diamond films at low temperature.

Atomic-scale imaging of insulating diamond through resonant electron injection

The electronic properties of insulators such as diamond are of interest not only for their passive dielectric capabilities for use in electronic devices, but also for their strong electron confinement on atomic scales. However, the inherent lack of electrical conductivity in insulators usually prevents the investigation of their surfaces by atomic-scale characterization techniques such as scanning tunnelling microscopy (STM). And although atomic force microscopy could in principle be used, imaging diamond surfaces has not yet been possible. Here, we demonstrate that STM can be used in an unconventional resonant electron injection mode to image insulating diamond surfaces and to probe their electronic properties at the atomic scale. Our results reveal striking electronic features in high-purity diamond single crystals, such as the existence of one-dimensional fully delocalized electronic states and a very long diffusion length for conduction-band electrons. We expect that our method can be applied to investigate the electronic properties of other insulating materials and so help in the design of atomic-scale electronic devices.