Charging of aerosol products during ferrocene vapor decomposition in N2 and CO atmospheres

Decomposition of ferrocene vapor in CO and N-2 atmospheres in the temperature range from 800 to 1150 degrees C leading to the formation of single-walled carbon nanotubes (CNTs) and maghemite (gamma-Fe2O3) particles, respectively, was investigated by means of a differential mobility analyzer (DMA) and Fourier transform infrared spectroscopy, transmission electron microscopy, and laser desorption ionization time-of-flight spectrometry. This allowed us to produce aggregated iron oxide particles with mobility diameters of 20-60 nm and bundles of single-walled CNTs with mobility diameters of 60-100 nm. The DMA measurements of iron oxide particles revealed an equal negative and positive natural single charging with similar bimodal size distributions. Increasing the temperature resulted in the increase of the total particle concentration and a slight decrease in the fraction of charged particles from 30% to 20%. It was found that CNTs form spontaneously charged (92-99% bundles carrying up to five elementary electrical charges. The concentration ratio between positively and negatively charged CNTs decreased from 6 to 1, increasing the temperature in the system from 800 to 1150 degrees C. The charging phenomenon can be explained by electron and ion emission owing to the surface minimization processes in both particles and CNTs, resulting in high-energy release.