Role of low-level impurities and intercalated molecular gases in the α particle radiolysis of polytetrafluoroethylene examined by static time-of-flight secondary-ion-mass spectrometery

The structural degradation of polytetrafluoroethylene (PTFE) upon irradiation with MeV alpha ( α ) particles is accompanied by the proliferation of hydrogenated and oxygen-functionalized fluorocarbon species. In this article, we explore the origin of monoxide- and dioxide-functionalized fluorocarbon species that emerge upon α particle irradiation of PTFE. Samples of neat PTFE were irradiated to α doses in the range of 10 7 – 5 × 10 10 rad using 5.5 MeV He 2 + 4 ions produced in a tandem accelerator. Static time-of-flight secondary-ion-mass spectrometry (TOF-SIMS), using a 20 keV C 60 + source, was employed to probe chemical changes as a function of α particle irradiation. Chemical images and high-resolution mass spectra were collected in both the positive and negative polarities. Residual gas analysis, utilized to monitor the liberation of molecular gases during α particle irradiation of the PTFE in vacuum, is discussed in relationship to the TOF-SIMS data.