In Situ Laser Light Scattering for Temporally and Locally Resolved Studies on Nanoparticle Trapping in a Gas Aggregation Source

Abstract

Gas phase synthesis of nanoparticles (NPs) via magnetron sputtering in a gas aggregation source (GAS) has become a well‐established method since its conceptualization three decades ago. NP formation is commonly described in terms of nucleation, growth, and transport alongside the gas stream. However, the NP formation and transport involve complex non‐equilibrium processes, which are still the subject of investigation. The development of in situ investigation techniques such as UV–Vis spectroscopy and small angle X‐ray scattering enabled further insights into the dynamic processes inside the GAS and have recently revealed NP trapping at different distances from the magnetron source. The main drawback of these techniques is their limited spatial resolution. To understand the spatio‐temporal behavior of NP trapping, an in situ laser light scattering technique is applied in this study. By this approach, silver NPs are made visible inside the GAS with good spatial and temporal resolution. It is found that the argon gas pressure, as well as different gas inlet configurations, have a strong impact on the trapping behavior of NPs inside the GAS. The different gas inlet configurations not only affect the trapping of NPs, but also the size distribution and deposition rate of NPs.

Time-resolved in situ nanoparticle size evolution during magnetron sputtering onto liquids

“…53 These very small primary clusters with low structural order grow via collisions and coalescence and form crystalline Ag NPs. Consequently, a bi-modal 8,32,57,58 and poly-disperse PSD would be expected due to the coexistence of very small and relatively large Ag NPs since fresh nucleation and ongoing nanocrystal growth processes simultaneously happen during the deposition period. 24,59…”

Gas-phase synthesis of nanoparticles: current application challenges and instrumentation development responses

“…Indeed, the latter was found to play the most important role in a very recent study by Drewes et al 23 probing the nanoparticle trapping very near the target with in situ Laser Light Scattering (LLS). Along with the gas inlet configuration, the inert gas (Ar) pressure was also found to determine the extent of trapping, which, in turn, affected the deposition rate and size distribution (Fig.…”

“…Of course, several studies on the latter subject had been published before the examined period; 17–19 however, it appears that this recent thrust is in full concord with simultaneous instrumentation advances in order to help resolve the very current challenge of limited nanoparticle yield (for example, see discussion on, 20 below). In parallel, intense research over the past five years revolved around improving precision in structural control (down to the atomic level) predicted by atomistic simulations, 21 obtained by source upgrades, 22 and assessed by in situ diagnostics; 23 therefore, these are the main themes of this perspective, with emphasis on the magnetron-sputtering inert-gas condensation technique.…”

Time-resolved in-situ nanoparticle size evolution during magnetron sputtering onto liquids

“…61 These very small primary clusters with low structural order grow via collisions and coalescence and form crystalline Ag NPs. Consequently, a bi-modal 8,33,64,65 and poly-disperse PSD would be expected due to the coexistence of very small and relatively large Ag NPs since fresh nucleation and ongoing nanocrystal growth processes simultaneously happen during the deposition period. 25,66 Particle size distributions…”