The absorption intensity and the peak wavelength of the 570-nm band, which is observed at LNT after fast neutron irradiation of MgO, vary appreciably depending on the concentrations of the impurities such as Fe or Mn, and the behavior of this band during isochronal annealing is characteristic. From these facts it may be proposed that the absorption at about 570 nm may be attributed to more than the two kinds of color centers.
The growth of the 352- and 975-nm bands, which accompany the zero-phonon lines at 361.8 and 1044nm, respectively, caused by fast neutron irradiation is controled by the addition of impurities.
The 351-nm band and the 338-nm line are observed at LNT in the CL cathodoluminescence spectra of the samples irradiated by protons and fast neutrons at the temperatures below LNT, but they are not observed of the sample irradiated at the temperatures higher than the room temperature. The half-width of the 338-nm line at LNT is 4.4A.
