M Centers in Potassium Bromide. I

Oriented distributions of M centers have been produced in KBr and the resulting anisotropic spectra measured at −76° and −194°C. Dichroic absorption bands are observed corresponding to transitions from the ground state to a variety of higher excited states. Included in these are previously unreported transitions that lie 0.7–1.1 eV to higher energy than the F band. Some energy-level assignments are made using the F2 model of the M center. A simplified treatment is presented for the interpretation of dichroic spectra arising from the optical dipole transitions of anisotropic centers in an otherwise isotropic lattice.