Kinetic aspects of the synthesis of Ag nanoparticles (NPs) by magnetron sputtering are studied by in situ and time‐resolved small angle X‐ray scattering (SAXS). Part of the NPs are found to become confined within a capture zone at 1–10 mm from the surface of the target and circumscribed by the plasma ring. Three regimes of the NP growth are identified: 1) early growth at which the average NP diameter rapidly increases to 90 nm; 2) cycling instabilities at which the SAXS signal periodically fluctuates either due to expelling of large NPs from the capture zone or due to the axial rotation of the NP cloud; and 3) steady‐state synthesis at which stable synthesis of the NPs is achieved. The NP confinement within the capture zone is driven by the balance of forces, the electrostatic force being dominant. On reaching the critical size, large NPs acquire an excessive charge and become expelled from the capture zone via the electrostatic interactions. As a result, significant NP deposits are formed on the inner walls of the aggregation chamber as well as in the central area of the target.
In‐situ UV–Vis spectroscopy was used for investigating the evolution of silver nanoparticles (NPs) inside the gas aggregation cluster source (GAS). The light beam probed the interior of the GAS at different distances from the magnetron. Plasmon resonance was detected at 365 nm, with the highest intensity found close to the magnetron due to the NP trapping. Time‐resolved measurements revealed that after the discharge switch off the majority of trapped NPs fly out of the GAS. Part of them is redeposited onto the center of the target due to the electrostatic force. NPs collected at the distance of 20 mm and further from the magnetron demonstrate gradual decrease of the size, pointing to the loss of bigger NPs on the walls.
Since the time of Faraday’s experiments, the optical response of plasmonic nanofluids has been tailored by the shape, size, concentration, and material of nanoparticles (NPs), or by mixing different types...
In this study, in situ UV-Vis spectroscopy is used to investigate the growth and transport of nanoparticles inside a gas aggregation source (GAS) dependent on the Ar gas flow and operating pressure. It was found that the nanoparticles were becoming trapped at different positions inside the GAS dependent on the gas flow. Moreover, in situ UV-Vis spectroscopy suggested the presence of large nanoparticles inside the GAS, which were not observed outside. Computational fluid dynamic simulations were performed to study the velocity distribution inside the GAS. Three distinct areas were identified, where nanoparticles can become trapped or lost. The gas flow velocity distribution was found to strongly impact the transport of nanoparticles.
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