The photoluminescence spectra of excitons which were bound to B804 iso-electronic defects (1.1068eV principal no-phonon line) were investigated in magnetic fields of up to 6T. The symmetry of these defects was found to be C3v. The ground state of the bound excitons was split into a doublet with an energy separation of about 40eV. The lowest state, which was not evident in the zero-field spectra, resulted in an additional spectral component in the magnetic field.

A.S.Kaminskii, E.V.Lavrov: Materials Science Forum, 1995, 196-201, 145-50