| Abstract
| - Context. Hydrogenated amorphous carbons, a-C:H, can incorporate a variety of heteroatoms, which can lead to interesting effects. Aims. We investigate the doping of interstellar a-C:H grains with, principally, Si, O, N and S atoms within the astrophysical context. Methods. A search of the literature on doped a-C:H reveals a number of interesting phenomena of relevance to astrophysics. Results. X dopants in a-C:H: X materials can affect the sp 3/sp 2 ratio ( X = Si, O and N), lead to blue photoluminescence (undoped or X = N), induce ferromagnetic-like behaviour ( X = N and S) or simply be incorporated (depleted) into the structure ( X = Si, O, N and S). Si and N atoms could also incorporate into fullerenes, possibly forming colour-centres that could mimic diffuse interstellar bands. Conclusions. Doped a-C:H grains could explain several dust-related conundrums, such as: “volatile” Si in photo-dissociation regions, S and N depletion in molecular clouds, blue luminescence, some diffuse interstellar bands and ferromagnetism in carbonaceous grains.
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