Optical and electron paramagnetic resonance spectra of silica glass implanted with oxygen ions

Oxygen ions (O+) were implanted into high purity silica glass, Coming 7940, at liquid nitrogen temperature and at energies of 50, 160 keV and 5 MeV, with a dose range from 1 X 10(15) to 3 X 10(16) ions/cm(2). Helium ions (He+) were also implanted into Coming 7940 at liquid nitrogen temperature and at 35 keV and 160 keV to doses of 1 X 10(17) ions/cm(2) to compare with O+ implantation. Optical absorption measurements were made on the ion implanted samples in the range of 1.8 to 6.2 eV. In samples O+ implanted at 50 and 160 keV, the optical density at around 2.0 eV was zero, while the optical densities increased with increasing photon energy, and absorption bands at around 3, 5 and 5.8 eV were resolved. Absorption bands at. 5 and 5.8 eV were resolved in the 5 MeV implanted sample and their absorbencies were higher by factor of more than 2 than those in the 50 and 160 keV implanted samples. For He+ implanted samples optical density increased as a function of photon energy up to 6 eV, and in addition a band at 5 eV was resolved in every sample. X-band electron paramagnetic resonance (EPR) spectra were measured at 77 K for oxygen-related centers and at room temperature for E' centers prior to and after ion implantation of samples. Two paramagnetic states, E' centers and peroxy radicals, were detected after O+ or He+ implantation. The peroxy radical (FOR) was the dominant defect in O+ implanted samples, while the numbers of E' centers and PORs induced in He+ implanted samples were the same. Since the detected numbers of PORs were < 2% of the number of implanted O+, most of the implanted O+ must exist in forms which have not yet been detected in EPR measurements. The 5 eV band, assigned to PORs, increased with increasing oxygen dose and was also larger when the implant energy was 5 MeV. A reaction between E' centers and oxygen is proposed.