Mass spectrometric study of ammonia/methane surface-wave plasma applied to low-temperature growth of carbon nanomaterials

We present a mass spectrometric study of NH3/CH4 surface-wave plasma (SWP) used for low-temperature synthesis of carbon nanomaterials (CNMs) with graphite-encapsulated Ni nanoparticles as a catalyst. Optical emission and mass spectra were analysed to understand the processes responsible for CNMs synthesis. We have shown that an optimum balance between etching by atomic hydrogen and CNMs synthesis by carbon-containing molecular species was achieved at a NH3/CH4 ratio of roughly 70/30% in SWP, where the highest number of hydrogen and carbon-containing molecular species in SWP are observed in the optical emission and mass spectrometry measurements.