“…However, if the 389 nm center is observed in spectra with obvious features of high temperature treatment (e. g. the 462 and 498 nm centers), then definitely the high temperature treatment was followed by irradiation. In this case the final irradiation treatment can be confirmed by the presence of characteristic radiation centers: GR1 (neutral vacancy, ZPL at wavelength 741 nm), ND1 center (negatively charged vacancy [31], ZPL at wavelength 393 nm) and TR12 center (ZPL at 471 nm, a defect related to self-interstitials).…”