Energy distributions of constituent atoms of cluster impacts on solid surface

Abstract

Using the time-evolution Monte Carlo simulation code DYACAT, the energy distributions of constituent atoms due to big cluster impacts on amorphous targets have been investigated, where the (Ag) n and (Al) n cluster (n being 10 to 500) with energies a few 100 eV/atom to keV/atom are bombarded on amorphous carbon and gold targets, respectively. It is found that the energy distribution of constituent atoms is strongly affected by the mass ratio M 2/M 1 (M 1 and M 2 being the atomic masses of the constituent atom and the target atom, respectively), the size of the cluster, and the cluster energy. In the case of the 1 keV/atom (Ag) 500 cluster impacts on C (M 2/M 1 < 1) the shape of the energy distribution of constituent atoms is trapezoidal, while in the case of the Al cluster impacts on Au (M 2/M 1 > 1) the high-energy tail of the energy distribution of Al atoms due to the big cluster impact ( n > 100) can be well described in terms of the Maxwell-Boltzmann function, and its temperature is linearly proportional to the energy. In the case of 1 keV/atom (Al) 500 cluster impact on Au, the quasi-equilibrium state continues for more than 0.6×10 −13 s, but the temperature of the cluster impact region decreases as time passes. The present simulation supports the recent Echenique, Manson and Ritchie's Ansatz in their theory of cluster impact fusion.