ION-BOMBARDMENT OF POLYETHYLENE

The bombardment of polyethylene by argon atoms is examined by molecular dynamics (MD) simulations. The radiation damage causes chain scission, cross linking and carbonisation of the target. The evolution of gas and loss of volatile species in the form of ejected clusters is analysed and the number and type of ejected molecules is quantified. The process by which these effects occur is discussed. It is found that a single impact trajectory may be divided into two parts, the first having a duration of under 0.4 picoseconds and the second lasting for many picoseconds. The initial impact causes bond breaking and sputtering of atoms and small hydrocarbon radicals. At later times recombination takes place between fragments remaining within the target, producing molecules of varying size that diffuse through the target and escape.