Spectral and structural properties of carbon nanoparticle forming in C 3O 2 and C 2H 2 pyrolysis behind shock waves

Abstract

The diversity of carbon particles, forming durin pyrolysis of C 3 O 2 and C 2 H 2 behind shock waves in thewide temperature range 1200–3800 K, was investigated. The process of condensed carbon particle formation was observed in situ by the multichannel registration of the time profiles of optical properties of media in the UV, visible, and near-IR ranges. Besides that, the probes of postshock materials, deposited on the walls of the shock tube, were analyzed bylow- and high-resolution transition electron microscopy (TEM) and by electron microdiffraction (MDF) measurements. The comparison of extinction properties of young growting particles with the electron microscopic analysis of solidified substance gave a notion about the peculiarities of carbon particle formation process from the diffeerent carbon-bearing gases at various temperatures. particles, forming from both substances at 1500–200 K, look similar to usual soot, and the absence of hydrogen in C 3 O 2 leads to faster formation and graphitization of particles. At the tempratures 2100–2600 K, the decrease of the paticle formation rate and the fall of final particle yield in all mixtures is observed. After C 3 O 2 pyrolysis experiments, gigantic film-like spheres with the size up to 700 nm were observed on the walls. The peculiarity of the high-temperature (2700–3200 K) process of carbon particle formation in C 3 O 2 pyrolysis is the high degree of crystallization of the final particles.