UV- and γ-sensitization of latent tracks in polyethylene terephthalate

Photosensitization of polymer polyethylene terephthalate (PET) bombarded with swift heavy ions (Xe) was studied. Ultraviolet (UV)- and γ-irradiation were used for sensitization. Infrared spectroscopy (IR) and reversed-phase high-performance liquid chromatography (HPLC) were used to study the radiolysis products in latent tracks (directly in the sample or in the etching solution). It was found that the exposure of the sample to ultraviolet light results in the transformation of the radiolysis products formed in the tracks into terephthalic acid. Surface defects, detected by AFM, were found to correspond to tracks; their form (cavities and hillocks) and size changing reflect the changing of latent track state. It was found that UV irradiation destroyed the cross-linked regions in the tracks. This process (photodecomposition) was shown to be the key stage of the UV sensitization and the main cause of etching rate increase. The γ-irradiation effect on track etching was found to be almost the same.