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 D-2 /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. (C) 2003 American Institute of Physics.