ABSTRACTSeveral highly disordered forms of carbon are termed “diamondlike” by virtue of their extreme hardness and significant optical gap. However, it is quite tempting to extend the analogy further and attribute these “diamondlike” properties to a high degree of local diamond order. Although an “amorphous diamond” character has been inferred from the optical properties in the 0-10 eV range, and the position of the π + σ plasmon peak in the electron energy loss spectrum, there is no direct evidence for such diamond order. However, there is a considerable body of work showing that DLC embodies a considerable degree of graphitic order which determines the optical gap and Raman spectrum. In order to determine to what extent a clearly non-diamond structure can exhibit specific “diamondlike” properties, we examine a simple structure derived from graphite. This “defected graphite” (DG) construct presumes an underlying graphitic structure which is insulating due to the strong localization of π -electrons by randomly distributed non-aromatic defects. Using specific defects suggested by experiment, the DG model reproduces a quite surprising array of observed properties of both hydrogenated and hydrogen-free “diamondlike” carbon.
