THE STRUCTURE OF IONOLUMINESCENCE SPECTRA FOR SILICA EXCITED BY HYDROGEN IONS

We carried out a mathematical treatment of the experimental silica ionoluminescence spectra in a visible wavelength range measured by us earlier under irradiation with 420 keV H(2)(+)ions. The irradiation was performed on Van de Graaff accelerator with the absorption dose up to 4.3.10(10 )Gy. To analyse the spectrum shapes we used a fitting procedure with the Gaussian functions. The mathematical treatment showed that the spectra were well fitted by three Gaussians with the maxima at 1.9, 2.3 and 2.7 eV. The position of the maxima did not change with the accumulation of hydrogen in the sample, which indicates that during the irradiation the light was excited by the same defect centres. Two obvious peaks correspond to well-known red and blue bands with maxima at 1.9 and 2.7 eV, which are associated with silica defects such as nonbridging oxygen hole centres and oxygen deficiency centres, respectively. As a result of the fitting procedure, the presence of another green band with a maximum at 2.3 eV (536 nm) was determined. The intensity of the band maximum increased with the growth of hydrogen absorption dose. It can be explained by the accumulation of hydrogen in the sample, and as a consequence, by change in the balance of silica defects.