COMPUTER EXPERIMENTS ON MOLECULAR EJECTION FROM AN AMORPHOUS SOLID - COMPARISON TO AN ANALYTIC CONTINUUM MECHANICAL MODEL

Molecular-dynamics simulations are performed to investigate the ejection into the gas phase of large molecules in an amorphous van der Waals solid due to a rapid expansion of a cylindrical "track" of material. Such an excitation geometry may be caused by a fast ion penetrating a solid. The ejection yield, the angular distribution of ejected particles, and the crater size are investigated as a function of the expansion rate and energy, sample thickness, and angle of incidence. Comparisons are made with results from an analytic continuum mechanical model which estimates the ejection from the transiently pressurized region. Although the model is described for point particles and is independent of excitation mechanism, it is able to describe many aspects of the simulation.