Collision dynamics of large water clusters on graphite

Abstract

Articles you may be interested inA molecular-beam study of the collision dynamics of methane and ethane upon a graphitic monolayer on Pt (111) The emission of neutral cluster fragments during collisions of large water clusters with graphite surfaces has been investigated using molecular beam techniques. Water clusters with an average size of up to 1.4•10 4 molecules per cluster collide with the surface with a velocity of 1380 ms Ϫ1 . Angular distributions for emitted large fragments are shifted towards the tangential direction and become increasingly narrow with increasing fragment size. The kinetic energy in the surface normal direction is efficiently transferred to internal degrees of freedom and to surface modes, while the momentum parallel to the surface plane is less affected by the surface interaction. Both a direct scattering channel and an emission channel mediated by cluster evaporation are concluded to be of importance for the collision outcome. The results for the evaporation-mediated emission channel agree well with previous experimental investigations and with recent molecular dynamics simulations, and the observations regarding the direct scattering channel qualitatively agree with the dynamics observed for macroscopic particles colliding with surfaces.

Scattering of Ice Particles from a Graphite Surface: A Molecular Dynamics Simulation Study

“…The calculations performed in the present study are of the same type as the ones presented in refs , , and 8, and for a detailed description we refer to these papers. The initial conditions were chosen to resemble the conditions during cluster beam experiments, where large water clusters impinged on a graphite surface at surface temperatures T surface ≤ 1400 K. In the experiments, the average incident cluster size was ≤ 14 000 monomers/cluster, but the distribution extended up to n > 20 000. We have simulated collisions between (H 2 O) n and graphite, where n has been set to 4094, 12 516, and 25 159 to mimic different parts of the incident size distribution in the experiments.…”

“…Clusters this large typically have diameters of a few nanometers and approach the macroscopic size range. Cluster beam experiments and MD simulations − have shown that when nanometer-sized water clusters collide with graphite, large fragments may leave the surface by means of two different mechanisms: evaporation-mediated emission and direct scattering. The evaporation-mediated mechanism is in operation at surface temperatures above 700 K and can be divided into three stages: (i) cluster deformation on surface impact, (ii) cluster heating by the hot surface, and (iii) cluster emission driven by evaporation of monomers and small fragments.…”

Molecular Dynamics Simulation of Water Nanodroplet Bounce Back from Flat and Nanopillared Surface

“…The MD simulations of impinging metal clusters, such as molybdenum, aluminum, and copper, were performed to investigate deposition, deformation, and fragmentation on the surface of the same metal species , and the rigid surface . Tomsic et al reported both experiments and MD simulations of impinging ice clusters on hot surfaces. − The evaporation and bouncing of the ice clusters were studied at surface temperatures between 300 and 1400 K. They found two types of bounce-back behaviors: evaporation and elastic bouncing. When the surface temperature was 1400 K, the impinging ice clusters, whose initial temperature was 180 K, were heated by the hot surface and bounced back due to evaporation of monomers and small fragments of water molecules on the surface .…”

Impact Desolvation of Polymers Embedded in Nanodroplets

“…The issue of droplet–wall collisions is of interest also in other fields of research, ranging from controlled cluster deposition over surface cleaning by cluster impact to cluster-impact chemistry . The fragmentation of pure droplets (without embedded macromolecules) has been studied previously for clusters composed of van der Waals-bonded atoms − and molecules , and, in particular, also for water. − The collision of a protein-loaded droplet with a wall has only rarely been studied before …”