The infrared characteristics investigation of carbon nitride films

Two series of a-C(N):H films, with diamond-like character and graphite-like character respectively, are prepared. Without N incorporation, the two kinds of films have very close IR bands in the range of 1000–1800 cm− 1. However, the difference in IR activity of the two series films became dramatical as N was introduced into both kinds of carbon films, which is attributed to purely electronic effect, the electronegativity of N. The N incorporated in carbon films is able to induce bond dipole of CC bonds in sp2 graphite cluster, leading to a degree of dipoles for all the aromatic sp2 CC bonds, a permanent electric dipole effect arises and this could lead to the increase in IR activity of the sp2 clusters. As the N content exceeds 20 at.% in the carbon films, strong conjugation of C≡N bonds with aromatic graphite rings can induce conjugated π bond dipole too.