Mechanical time-of-flight filter based on slotted disks and helical rotor for measurement of velocities of nanoparticles

Abstract

A mechanical time-of-flight filter intended for measurement of velocities of nanoparticles exiting a gas aggregation source has been developed. Several configurations maximizing simplicity, throughput or resolution are suggested and investigated both theoretically and experimentally. It is shown that the data measured using such filters may be easily converted to the real velocity distribution with high precision. Furthermore, it is shown that properly designed filters allow for the monitoring of the velocity of nanoparticles even at the conditions with extremely low intensity of the nanoparticle beam.

Plasmonic Ag/Cu/PEG nanofluids prepared when solids meet liquids in the gas phase

“…It involves: (1) sputtering of a metal target; (2) nucleation and growth of NPs in the gas phase; (3) transport of NPs by the gas ow; (4) deposition of NPs on the liquid surface; (5) their penetration through the vacuum/ liquid interface and diffusion into the bulk of the liquid. Although not very extensively, stages 1-4 have already been studied, both experimentally 27,28,51 and theoretically. 52 Stage 5 has been investigated to an even lesser extent due to technical challenges associated with in situ analysis of liquids under vacuum.…”

“…As was shown earlier, metal NPs exit the GAS at velocities in the range of tens of m s −1 and thus deposit on substrates in a so-landing regime, for which the kinetic energy is not sufficient to induce any change in the NP morphology and structure. 51 On solid substrates, the NPs accumulate and build up a mesoporous deposit. However, if liquid PEG is used as a For this particular system, we selected the stoichiometric non-polar oxygen-terminated surface, (111):O, which has been reported to be the most stable surface.…”

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

“…Finally, moving outside the condensation chamber, in two similar studies, Solar ˇet al utilized a very simple, 3D-printed mechanical time-of-flight filter to measure the velocities of Cu nanoparticles prior to being coated by sequential sputtering or to their deposition onto a support. 104,105 Knowing the velocity distribution function of a cluster beam can be very important, as it may affect the final configuration in case of coating (e.g., core-shell vs. core-satellite), or the soft-or hard-landing upon deposition. However, previous attempts typically utilised electrostatic filters, which have the inherent limitation of not taking into account the aforementioned multiplicity in electrical charge carried by the nanoparticles in the beam.…”

A novel method for the synthesis of core–shell nanoparticles for functional applications based on long-term confinement in a radio frequency plasma

“…The achievable coating thickness is limited by the maximum power, which can be applied to the target and the residence times dened by the strength of the gas ow. Investigations by Solař et al 37 on the exit velocity of NPs have shown that for typical operating conditions even mean velocities of up to 93 m s −1 are possible. Therefore, special experimental measures have to be taken in order to increase the residence time of the particles in the secondary coating region, e.g., by injecting additional argon gas.…”