Solid films composed principally of carbon and nitrogen were grown on a variety of substrates at ambient temperature in a flow-tube reactor by upstream mixing of cyanogen azide, cyanogen, or cyanogen halides with active nitrogen obtained from an electrical discharge. Ab initio calculations and dependence of deposition rates on both choice of donor and N atom production suggests that NCN radicals are a critical growth species. The films obtained are electrically insulating with a refractive index of 2.3 at visible wavelength and are optically transparent from 550 nm out to at least 14 mu m with the exception of two broad absorption bands centered at 1550 and 3250 cm(-1), the latter band growing in upon exposure of the film to atmospheric moisture. Film analysis by X-ray photoelectron spectroscopy revealed comparable concentrations of both carbon-to-nitrogen bonds (with approximate C3N4 stoichiometry) and diamond-like carbon-to-carbon bonds as well as minority bonding of carbon to impurities.