Influence of the bath gas on the condensation of supersaturated iron atom vapour at room temperature

The influence of the kind of bath gas and its pressure on the iron nanoparticle formation and growth was investigated experimentally. Iron nanoparticles were synthesized from supersaturated iron vapour generated by ArF excimer laser pulse photolysis of gaseous Fe( CO) 5 at room temperature. The particle size was determined by time-resolved laser-induced incandescence (TiRe-LII) as a function of time after photolysis at different experimental conditions. Additionally, final particles were sampled and analysed by transmission electron microscopy and by energy-dispersive x-ray analysis. The particle growth rate and the final particle size depended on the bath-gas composition and pressure. Increasing the argon bath-gas pressure accelerated the iron nanoparticle growth rate. In contrast to argon, no influence of helium on the particle growth rate was observed. The experimental results are compared with numerical simulations of particle surface growth, based on the model developed in previous investigations. The simulations indicate that the observed differences in the influence of the bath gas on the particle formation are caused by the species-dependent quenching probability of the active atom-particle complexes by the bath gas.