ION-BOMBARDMENT OF POLYETHYLENE

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