Application of Extended Smoluchowski Equations to Formation of Silver Nanoclusters Generated by Direct Current Magnetron Sputtering Source

We apply the extended Smoluchowski rate equations with neutralization process between nanocluster (NC) anion and cation to study the formation of silver NCs generated by direct current magnetron sputtering (DC-MSP). By comparing the experimental and simulation results, it was found that the origin of size tuning by the cell length was prolonged aggregation time. Size tuning by DC power (P) was attributed to the enhanced initial number density and ionization fraction of the sputtered materials. It was revealed that parts of NC ions were "lost" after aggregation and the amount of lost ions increased with power (20 W < P < 100 W), which was caused by the accelerated neutralization process. The high consistency between experiment and simulation suggests that the extended Smoluchowski rate equations are capable to describe the NC formation in gas phase.