Evidence for trans-polyacetylene in nanocrystalline diamond films from H–D isotropic substitution experiments

Raman spectra of nanocrystalline diamond (NCD) films show a peak around 1140 cm−1 that is usually considered to be a fingerprint of a NCD phase in the sample. From recent studies, it was suggested that this line is due to trans-polyacetylene in the films. We present Raman spectra of deuterated NCD films produced from a D2/CD4/Ar plasma. In these spectra, the 1140 cm−1 mode has disappeared and a peak at 860 cm−1 has emerged. The downshift of the peak at 1140 cm−1 is taken as a proof for its origin from trans-polyacetylene.