15 research outputs found
Reentrant Adhesion Behavior in Nanocluster Deposition
We simulate the collision of atomic clusters with a weakly attractive surface
using molecular dynamics in a regime between soft-landing and fragmentation,
where the cluster undergoes large deformation but remains intact. As a function
of incident kinetic energy, we find a transition from adhesion to reflection at
low kinetic energies. We also identify a second adhesive regime at intermediate
kinetic energies, where strong deformation of the cluster leads to an increase
in contact area and adhesive energy.Comment: 7 pages, 6 figure
Molecular dynamics simulations of reflection and adhesion behavior in Lennard-Jones cluster deposition
We conduct molecular dynamics simulations of the collision of atomic clusters
with a weakly-attractive surface. We focus on an intermediate regime, between
soft-landing and fragmentation, where the cluster undergoes deformation on
impact but remains largely intact, and will either adhere to the surface (and
possibly slide), or be reflected. We find that the outcome of the collision is
determined by the Weber number, We i.e. the ratio of the kinetic energy to the
adhesion energy, with a transition between adhesion and reflection occurring as
We passes through unity. We also identify two distinct collision regimes: in
one regime the collision is largely elastic and deformation of the cluster is
relatively small but in the second regime the deformation is large and the
adhesion energy starts to depend on the kinetic energy. If the transition
between these two regimes occurs at a similar kinetic energy to that of the
transition between reflection and adhesion, then we find that the probability
of adhesion for a cluster can be bimodal. In addition we investigate the
effects of the angle of incidence on adhesion and reflection. Finally we
compare our findings both with recent experimental results and with macroscopic
theories of particle collisions.Comment: 18 pages, 13 figure
Hybrid method for modeling epitaxial growth: Kinetic Monte Carlo plus molecular dynamics
We conduct molecular dynamics simulations of the collision of atomic clusters with a weakly attractive surface. We focus on an intermediate regime, between soft landing and fragmentation, where the cluster undergoes deformation on impact but remains largely intact and will either adhere to the surface (and possibly slide) or be reflected. We find that the outcome of the collision is determined by the Weber number We, i.e., the ratio of the kinetic energy to the adhesion energy, with a transition between adhesion and reflection occurring as We passes through unity. We also identify two distinct collision regimes: in one regime, the collision is largely elastic and deformation of the cluster is relatively small, but in the second regime, the deformation is large and the adhesion energy starts to depend on the kinetic energy. If the transition between these two regimes occurs at a similar kinetic energy to that of the transition between reflection and adhesion, then we find that the probability of adhesion for a cluster can be bimodal. In addition, we investigate the effects of the angle of incidence on adhesion and reflection. Finally, we compare our findings both with recent experimental results and with macroscopic theories of particle collisions
A kinetic Monte Carlo study of Pt on Au (111) with applications to bimetallic catalysis
Pt-decorated Au nanostructures and bimetallic PtAu nanoparticles have been shown to act as catalysts. Consequently we investigate the formation of extended Pt decorations of an Au island edge on Au(111) as possible catalysts. The investigation is by simulation using the kinetic Monte Carlo method. The effects of varying the rate of deposition of Pt atoms and the simulation temperature on the morphology of the resulting Pt nanostructures were investigated. The thickness and roughness of the nanostructures are readily influenced, with temperature being the more important factor. A combination of both high temperature and low deposition rate was the most effective at reducing the roughness. PtAu alloying in the Au island edge was identified. This work is (to the best of our knowledge) the first kinetic Monte Carlo simulation study of the formation of Pt nanostructures on Au. We demonstrate how the morphology of the Pt nanostructures can be controlled. The nanostructures studied here, comprising an adjustable mix of Pt overlayers and novel 1D PtAu surface alloys, are expected to be of considerable interest as potential bimetallic nano-catalysts
PR3: A system For radio-interferometry and radiation measurement on sounding rockets
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