Abstract:
We present here a novel experimental study of changes after contact electrification in the
optical transmission spectra of samples of both pristine and irradiated PET film treated with Kr+15
ions of energy of 1.75 MeV and a fluence of 3 × 1010 cm2
. We used a non-standard electrification
scheme for injecting electrons into the film by applying negative electrodes to both its surfaces and
using the positively charged inner regions of the film itself as the positive electrode. Electrification
led to a decrease in the intensity of the internal electric fields for both samples and a hypsochromic
(blue) shift in their spectra. For the irradiated PET sample, electrification resulted in a Gaussian
modulation of its optical properties in the photon energy range 2.3–3.6 eV. We associate this Gaussian
modulation with the partial decay of non-covalent extended conjugated systems that were formed
under the influence of the residual radial electric field of the SHI latent tracks. Our studies lead us
to suggest the latent track in the PET film can be considered as a variband material in the radial
direction. Consideration of our results along with other published experimental results leads us to
conclude that these can all be consistently understood by taking into account both the swift and slow
electrons produced by SHI irradiation, and that it appears that the core of a latent track is negatively
charged, and the periphery is positively charged.
