Heavy ion tracks in polymers and induced radicals

It has been known well that the etched tracks were observed with a microscope, after selectively etching the polymeric film irradiated by the heavy ions. However, there have been a few chemical researchs of why the tracks in a polymer show a large solubility and what kind of characteristic of a heavy ion the etching of tracks depend on. In order to investigate the life of radicals from growth to decay, the experiments were carried out keeping the specimen at low temperature from irradiation by heavy ions to measurement with ESR. It was found that the irradiation by heavy ions gave almost the same effect as that by the secondary electrons, like the gamma-ray irradiation. The heavy ion irradiation was supposed to cause the polymeric crystalline structure in tracks to be almost amorphous phase and so the life of radicals to be shorter. The radical densities for Br and Cl ions were larger than that for C ion. But, the threshold value to find the etched tracks remained undetermined. (author)