RADIAL-DISTRIBUTION FUNCTION OF AMORPHOUS-CARBON

The radial distribution function obtained by neutron diffraction on amorphous carbon films is compared to recent theoretical models. The first-neighbor peak is found to be quite broad for an amorphous semiconductor, in qualitative agreement with the predictions of molecular dynamics. However, the detailed shape of the first two peaks, including contributions in the minimum region, differs from all current models. Although the areas of the first two peaks indicate predominant threefold bonding, no evidence for a distinct peak associated with graphitelike, intrahexagon, third neighbors is observed. This distinguishes amorphous carbon from local two-dimensionally ordered graphitelike materials. © 1990 The American Physical Society.