Electronic and vibrational structures of amorphous carbon nitrides

Carbon nitrides are much more complicate alloys than amorphous carbons and additional effects related to the nitrogen incorporation should be considered. This work will review how the den sity-of-electronic-states (DOS), the optical properties and the electron-spin-resonance features may be understood on a common basis by observing that nitrogen inclusion often leads to lone-pair (LP) electrons formation and sp(1) hybridisation. We will give a picture of the DOS of amorphous carbon nitrides in the Vis-near UV energy range and use it to evaluate the complex dielectric constants, as determined by the transitions involving the LP electrons. We will show that understanding the role of LP is necessary in order to understand the optical properties of carbon nitrides both in the visible and in the infrared (IR) photon energy ranges. In the IR, the extra-electrons related to nitrogen (i.e. the LPs) will effect the medium-range polarisation and lead to the sharp vibrational absorption features at 1000-1900 cm(-1). (C) 2003 Elsevier Science B.V All rights reserved.