Stoichiometry evolution of polyethylene terephtalate under 3.7MeV He+ irradiation

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 2011-01, Vol.269 (2), p.140-144
• Main Authors: Abdesselam, M., Stoquert, J.P., Djebara, M., Cerruti, C., Chami, A.C., Montgomery, P.
• Format: Article
• Language: English
• Subjects: Carbon; Fluence; Ion beams; Irradiation; Mathematical models; Polyethylene terephthalates; Polyethylenes; Stoichiometry
• ISSN: 0168-583X
• DOI: 10.1016/j.nimb.2010.10.002

A 3.7MeV He+ ion beam was simultaneously used for Polyethylene Terephtalate (PET) film degradation and characterization. To enhance the potentialities of the characterization method, a multi-detector Ion Beam Analysis (IBA) technique was used. The stoichiometry change of the PET target following the irradiation is quantified at a beam fluence varying between 7A-1013 and 1.8A-1016 He+ cma degree 2. The damage induced in PET films by He+ bombarding was analyzed in-situ simultaneously through Rutherford Backscattering Spectrometry (RBS), Particle Elastic scattering Spectrometry (PES) and Hydrogen Elastic Recoil Detection (ERD). Appropriate experimental conditions for the observation of absolute changes in composition and thickness during irradiation were determined. The oxygen and carbon content evolution as a function of the ion fluence was monitored by He+ backscattering whereas the hydrogen content was measured by H( alpha ,H) alpha collisions in which both the scattered He+ ions and the recoiling H could be observed. The present study reveals that, at the highest fluence 1.8A-1016 He+ cma degree 2, the PET films have lost approximately 15% of the carbon, more than 45% of the hydrogen and 85% of the oxygen of the amount contained in the pristine sample. The energy shift of recoiling H+ ions at a forward angle 45A degree was followed in order to study the mass loss effect. The experimental results are consistent with the bulk molecular recombination model. Based on the results, hydrogen, oxygen and carbon release cross sections are determined. For hydrogen, comparison with deuteron irradiation indicates a cross section linear dependence on the stopping power.