Studies of Centers Produced in Sapphire and Ruby by Gamma Radiation
Document ID: 249
Doctoral Dissertation
North Carolina State University, Raleigh NC
Physics Department
Abstract
The centers produced by gamma radiation in sapphire and ruby crystals have been studied using several experimental techniques, The optical absorption of gamma-radiation-induced center bands has been studied using plane polarized light to investigate the optical properties along axes perpendicular and parallel to the C-axis. This technique allows determination of the anisotropy of the radiation-produced centers. Optical absorption bands were produced by gamma irradiation in the sapphire samples at approximately 6.0, 5.5, 4.2 and 3,0 ev for absorption measurements with the plane of polarization parallel to the C-axis. For absorption measurements with the plane of polarization perpendicular to the C-axis, the gamma-radiation-produced bands were found at approximately 6.0, 5.6, 4.55 and 3.1 ev. The optical absorption spectra were resolved into Gaussian curves using a computer reduction. The 6 ev absorption band, which has not previously been reported in gamma-irradiated sapphire, is associated with an electron bound at an interstitial aluminum ion. The band at 3 ev together with its anisotropy were found to correspond well with the predic~ion of Bartram et al. (1965) based on ESR studies of a center which was attributed to an 0 adjacent to a charge deficient cation site. The optical absorption studies of the irradiated ruby samples showed that prominent center bands occur at 2.64, 4.30, 5.84 and 6.1 ev. The center bands at 2.64 and 4.3 ev possess negative anisotropy and the 5.84 ev band exhibits positive anisotropy. In addition, the results of studies of glow curve measurements, thermoluminescent emission, electrical conduction and step annealing experiments are reported and discussed for the centers produced in ruby and sapphire crystals by gamma radiation. Also, the thermal activation energies of the sapphire centers have been calculated by three different methods and were found to be in agreement.
Keywords: laser, gamma radiation, color centers
| Citation: | C. R. Philbrick, "Studies of Centers Produced in Sapphire and Ruby by Gamma Radiation", North Carolina State University, Raleigh, NC, United States, Doctoral Dissertation, August 1966, 110 pages |