NEUTRAL AND ION EMISSIONS ACCOMPANYING PULSED EXCIMER-LASER IRRADIATION OF POLYTETRAFLUOROETHYLENE

The neutral and charged species emitted by pulsed-laser irradiation of polytetrafluoroethylene (PTFE) at 248 nm in vacuum have been examined . In particular, the species and properties of the emission products p roduced at typical fluence regimes used in the pulsed-laser deposition of PTFE thin films have been characterized. The relative intensities of the major products as well as their dependence on laser fluence are presented, and a simple model is used to fit the observed fluence dep endence. Evidence that the major neutral component, the monomer (C2F4) , is formed from a thermally activated unzipping reaction is presented . The ionic species are derived from the neutral decomposition product s, apparently ionized by electron collisions in the weak plasma genera ted at the target surface.