Electron spin resonance study of ion-implanted polymers

Abstract

The effect of ion implantation on the polymers PAN (polyacrylonitrile), PPO (poly 2,6-dimethylphenylene oxide) and PPS (p-polyphenylene sulfide) is studied using electron spin resonance. ESR measurements on these polymers were performed as a function of ion species and fluence in the temperature range 10 <T< 300 K. The unpaired carrier concentration increases with increasing fluence and is independent of the ion species used for implantation in this study (⁸⁴Kr,⁸⁰Br,⁷⁵As,⁴⁰Ar and¹⁴N). It is therefore concluded that the carrier concentration is related to the structural damage and not to chemical doping effects. From the shape of the ESR line, the ratio of the relaxation times for one-dimensional to three-dimensional spin diffusion is determined to be larger than 1000. The temperature dependence of the unpaired carrier concentration shows a strong deviation from a Curie law behavior, which can be explained by assuming that a defect band is formed with a bandgap due to strong Coulomb interaction between electrons on the defect sites.