“…Based on an extensive survey of previous literature, especially on plasma‐deposited SiC x N y and CN x films, we have assigned the band at 2,080 cm −1 to the stretching vibration of C‐ and N‐containing cumulated double‐bonded species. In particular, the stretching vibrations for ketene imines (>C=C=N–) range from 2,000–2,060 cm −1 , and for diazo groups (>C=N + =N − ) from 2,000‐2,200 cm −1 . Given that these vibrational frequencies can shift by tens of wavenumbers depending on their back bonding, it is very likely that the vibrational band at ~2,080 cm −1 is due to contributions from these two species .…”