Argon cluster size-dependence of sputtering yields of polymers: molecular weights and the universal equation

An analysis is provided of the data of Cristaudo et al. for the sputtering yields of polystyrene and polymethylmethacrylate by argon cluster ion beams as a function of their molecular weight. This analysis is made using the universal sputtering equation of Seah to evaluate the effect of the end-group density on the parameter A. This parameter is thought to be related to the average energy per atom (excluding hydrogen) to liberate fragments and it is shown that A decreases as the end-group density rises in the manner expected. Equations are provided relating A to the molecular weight or the end-group density that are obeyed for both materials. Copyright (c) 2014 Crown Copyright.