Erosion of FEP Teflon and PMMA by VUV Radiation and Hyperthermal O or Ar Atoms

A combination of beam-surface-scattering, quartz-crystal-microbalance, and surface-recession experiments was conducted to study the effects of various combinations of O atoms [in the O(P-3) ground state], Ar atoms, and vacuum ultraviolet (VUV) light on fluorinated ethylene-propylene copolymer (FEP) Tenon and poly(methyl methacrylate) (PMMA). A laser-breakdown source was used to create hyperthermal beams containing O and O-2 or Ar. A D-2 lamp provided a source of VUV light. O atoms with 4 eV of translational energy or less did not react with a pristine FEP Tenon surface. Volatile O-containing reaction products were observed when the O-atom energy was higher than 4.5 eV, and the signal increased with the O-atom energy. Significant erosion of FEP Teflon (similar to 20 % of Kapton H) was observed when it was exposed to the hyperthermal O/O-2 beam with an average O-atom energy of 5.4 ev. FEP Teflon and PMMA that were exposed to VUV light alone exhibited much less mass loss. Collision-induced dissociation by hyperthermal Ar atoms also caused mass loss, similar in magnitude to that caused by VUV light. There were no observed synergistic effects when VUV light or Ar bombardment was combined with O/O-2 exposure. For both FEP Tenon and PMMA, the erosion yields caused by simultaneous exposure to O/O-2 and either VUV light or Ar atoms could be approximately predicted by adding the erosion yield caused by O/O-2, acting individually, to the erosion yield caused by the individual action of either VUV light or Ar atoms.