Nanoparticle formation from supersaturated carbon vapour generated by laser photolysis of carbon suboxide

摘要

In this work particle formation and growth from condensation of supersaturated carbon vapour was investigated. Atomic carbon vapour was generated under well-controlled conditions from UV-laser pulse photolysis of C3O2 at 193 nm. Particle formation and growth were studied in a wide range of conditions with varying carbon vapour concentration, bath gas composition and pressure. The formation of particulate matter was observed as a function of time by laser light extinction. Particle sizes were determined in situ by time-resolved laser-induced incandescence and ex situ by transmission electronic microscopy. The characteristic time of particle growth was 20-1000 mu s. The final particle size was 5-12 nm, increased with pressure, and depends on bath gas composition. We propose a simple model for the description of carbon vapour condensation that assumes condensation of individual atoms on the cluster surface as the main growth mechanism. The comparison of experiments and simulations provides information about the initial concentration of carbon clusters for the different mixture conditions.