Linearity and additivity in cluster-induced sputtering: A molecular-dynamics study of van der Waals bonded systems

Abstract

Using molecular-dynamics simulation, we study sputtering of a condensed-gas solid induced by the impact of atomic clusters with sizes 1 ഛ n ഛ 10 4 . Above a nonlinear onset regime, we find a linear increase of the sputter yield Y with the total energy E of the bombarding cluster. The fitting coefficients in the linear regime depend only on the cluster size n such that for fixed bombardment energy, sputtering decreases with increasing cluster size n. We find that to a good approximation the sputter yield in this regime obeys an additivity rule in cluster size n such that doubling the cluster size at the same cluster velocity amounts to doubling the sputter yield. The sputter-limiting energy ⑀ s is introduced which separates erosion ͑⑀ Ͼ ⑀ s ͒ from growth ͑⑀ Ͻ ⑀ s ͒ under cluster impact.

Molecular Dynamics Simulations of Energetic Ar Cluster Bombardment of Ag(111)

“…2a, the total sputtering yield increases with the primary kinetic energy if the projectile size is kept constant. Such behaviour has already been reported in the previous studies with cluster projectiles [7,8]. It has been also observed that above certain threshold energy, the yield increases linearly with the kinetic energy [7,8].…”

“…3, our data support this observation again only partially. Indeed, below ε ≈ 300 eV/nucleon Y n dependence on ε is similar to the trend reported in [7,8]. However, at larger ε there is a distinctive deviation from this trend and ultimately the yield per nucleon even decreases with the increase of ε.…”

“…projectile ε [7,8]. In such representation, the data points for Y n collected with various clusters and kinetic energies can be placed on a single curved line with a positive slope with ε.…”

“…Mathematical form of this relation can be, however, greatly simplied if the total sputtering yield per projectile nucleon Y n is plotted as a function of the kinetic energy per nucleon ε. In such representation, the data points corresponding to various kinetic energies and projectiles can be placed on a single curve [7,8].…”

Dust-aggregate impact into granular matter: A systematic study of the influence of projectile velocity and size on crater formation and grain ejection

“…A number of simulation studies and experiments were performed on the impact of atomic clusters on atomic targets -for example, metals, but also organic targets -with the aim of exploring the dependence of the crater sizes and sputter yields on the projectile characteristics (Anders et al 2004;Samela & Nordlund 2008;Anders et al 2009;Anders & Urbassek 2013;Seah 2013;Seah et al 2014). In these studies it was found that -above a threshold regime -the main projectile characteristic affecting crater volume and ejection yield is the total projectile energy.…”