Luminescence of SiO2 quartz induced by swift heavy ion irradiations

We have studied the luminescence of natural SiO2 quartz induced by irradiations with heavy ions in the MeV amu(-1) range. The spectra obtained with sample temperatures of similar to 85 K have the same features and line shapes, irrespective of the fluence (phi t) and electronic stopping power (S-e) of the different ions (from C-12 to I-127). The spectra are least-squares fitted with three Gaussian functions centered at 440 nm (2.8 eV), 500 nm (2.5 eV), and 740 nm (1.65 eV). When increasing phi t, the intensities (I) of all three bands decrease and the decrease is fitted by, approximately, an exponential law, i.e., I = I-o exp(-sigma phi t), with approximately the same decay cross-section (sigma). sigma is found to increase by one order of magnitude when increasing 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 cross-section by one order of magnitude and does not vary versus S-e. These data are interpreted by the interactions of the self-trapped excitons (STEs) with the ion-induced defects increasing the non-radiative recombinations of the STEs. (C) 1997 Elsevier Science B.V.