LUMINESCENCE OF SIO2 QUARTZ INDUCED BY SWIFT HEAVY-ION IRRADIATIONS

We have studied the luminescence of natural SiO2 quartz induced by irr adiations with heavy ions in the MeV amu(-1) range. The spectra obtain ed with sample temperatures of similar to 85 K have the same features and line shapes, irrespective of the fluence (phi t) and electronic st opping power (S-e) of the different ions (from C-12 to I-127). The spe ctra are least-squares fitted with three Gaussian functions centered a t 440 nm (2.8 eV), 500 nm (2.5 eV), and 740 nm (1.65 eV). When increas ing phi t, the intensities (I) of all three bands decrease and the dec rease is fitted by, approximately, an exponential law, i.e., I = I-o e xp(-sigma phi t), with approximately the same decay cross-section (sig ma). sigma is found to increase by one order of magnitude when increas ing S-e above the amorphous track formation threshold at 2.5 keV nm(-1 ). Above this threshold, sigma is also larger than the track core cros s-section by one order of magnitude and does not vary versus S-e. Thes e data are interpreted by the interactions of the self-trapped exciton s (STEs) with the ion-induced defects increasing the non-radiative rec ombinations of the STEs. (C) 1997 Elsevier Science B.V.