Carbon 'fluffy' aggregates produced by helium - hydrocarbon high pressure plasmas as analogs to interstellar dust

Abstract

The present study provides an investigation on the deposition of carbon-related products on different substrates using a high power dielectric barrier discharge fed with helium and saturated hydrocarbon gases. The discharge has been characterized by means of voltage-current measurements, while the neutral species and the dissociation compounds accumulated in the plasma reactor have been analyzed by Fourier-transform infrared (FTIR) spectroscopy. The properties of non-aromatic hydrogenated amorphous carbon (a-C:H) films and 'fluffy' carbon dust deposited onto various substrates are analyzed by FTIR and X-ray photoelectron spectroscopy. The sp2-hybridized fraction of a-C:H films is negligible while for the 'fluffy' dust, does not exceed 10%. The microscopic appearance, the hierarchical organization and the CH2 / CH3 ratio around 2 of the 'fluffy' dust analog are results that supports the current understanding of cosmic carbon dust physico-chemical properties.