Particle size dependence of chemical compositions of metal-containing ultrafine particles synthesized from a gaseous mixture of iron pentacarbonyl and carbon disulfide

From a gaseous mixture of Fe(CO)5 and CS2, sedimentary aerosol particles involving organometal compounds were produced under UV light irradiation at 313 nm. By shortening the irradiation time of UV light, the particle size was effectively diminished to as small as 58 nm. From the analysis of the chemical structure by EDX-SEM and FT-IR spectra, chemical compositions of the particles smaller than 80 nm were found to be different from those of larger particles in that more CO groups were evolved, suggesting that the chemical reactions during the nucleation process were different from those during the propagation process. Chemical reactions during aerosol particle formation were discussed based on the chemical compositions of the sedimentary particles, and formation of sulfur-bridged Fe clusters was suggested during the nucleation process. By post-exposure with 266 nm light upon the deposited particles, volatile fragments such as Fe(CO)n (n = 1–3) were evolved in addition to CO.