Optical studies of nitrogen doped amorphous carbon: Laboratory and interstellar investigations

Measurements of plasma generated amorphous carbon films (a and a) in our laboratory show that nitrogen doping of the carbon imparts infrared activity to the films. In particular, the Raman G and D bands which are infrared inactive in typical amorphous carbons become active when nitrogen is substituted for carbon. This increase in infrared activity is attributed to a symmetry breaking by the nitrogen centers. In this paper we show that this symmetry breaking also gives rise to increases infrared emission. We suggest this same mechanism may be relavent to the origin of diffuse interstellar infrared emission from carbonaceous dust.