Influence of source parameters on the growth of metal nanoparticles by sputter-gas-aggregation

Abstract

We describe the production of size-selected manganese nanoclusters using a magnetron sputtering/aggregation source. Since nanoparticle production is sensitive to a range of overlapping operating parameters (in particular, the sputtering discharge power, the inert gas flow rates, and the aggregation length), we focus on a detailed map of the influence of each parameter on the average nanocluster size. In this way, it is possible to identify the main contribution of each parameter to the physical processes taking place within the source. The discharge power and argon flow supply the metal vapor, and argon also plays a crucial role in the formation of condensation nuclei via three-body collisions. However, the argon flow and the discharge power have a relatively weak effect on the average nanocluster size in the exiting beam. Here the defining role is played by the source residence time, governed by the helium supply (which raises the pressure and density of the gas column inside the source, resulting in more efficient transport of nanoparticles to the exit) and by the aggregation path length.

Interaction of a Low-Power Laser Radiation with Nanoparticles Formed over the Copper Melt in Rarefied Argon Atmosphere

“…The experiments showed that the rate of the reflectance decrease is greater in the case of a relatively large pressure of argon in the vacuum chamber. The results obtained for the effect of argon pressure agree well with the data of Reference [19] on the important role of argon atmosphere in the formation of condensation nuclei. Note that the minimum value of relative reflectance observed at the final stage of copper melting is equal to R min n ≈ 0.04 for both values of argon pressure.…”

Shape control of size-selected naked platinum nanocrystals

“…Interestingly, the mean particle size increases throughout the full range of the nanoparticle transit times and the evolution can be fitted to a single exponential relationship. This phenomenon suggests strongly that the increase in particle size is likely due to adatom condensation on the existing nanoparticle nuclei which is enhanced due to longer effective transit time 18 . We also see that the mass spectra are largely symmetrically distributed, closer to Gaussian than log-normal distribution, suggesting that the possibility of nanoparticle size increase through He-enhanced two-body collision of Pt nanoparticles is also small 19 .…”

Inserting Hydrogen into Germanium Quantum Dots

“…An estimate provides a mean diameter of about 6.5 nm with a width of 1.3 nm, which is considerably monodisperse. It is well known that the presence of a low-molecular-weight gas during aggregation of the nanoparticles in the cluster source results in smaller sizes, as for example observed for manganese particles . Because the light molecules increase the gas flow, the transport of nanoclusters is promoted, leading to less aggregation time in the interior of the aggregation volume.…”