Effects of MeV energy titanium ion implants on the oxygen related defects centers in silica

Silica samples were implanted with 4 MeV Ti2+ ions at nominal doses ranging from 0.1 to 5.0 x 10(15) cm(-2). Optical absorption was measured from 3.5 to 6.5 eV and in all spectra a local maximum at 5.0 eV and a shoulder at 5. 9 eV were observed. A second series of samples was implanted with 4 MeV Si2 + ions at nominal doses ranging from 0.5 to 3.0 x 10(15) cm(-2). Based on t he literature we assumed that Gaussian bands at 4.8, 5.01, 5.17, 5.88, and 7.15 eV comprised the observed spectra. Using Gaussian functions as basis s tates, linear fits to the data were performed yielding amplitudes for each band. Between 3.5 and 5.5 eV the fits were within +/-3%. At larger energies the fits were unsatisfactory. Non-linear fits with an additional, fully ad justable Gaussian function yielded a band at 6.4 eV with full width at half maximum similar to 0.5 eV and reduced the difference between the fit and t he data to <2% over the full range of the measurements. (C) 2000 Elsevier S cience B.V. All rights reserved.