g-Factor calculations for the species occurring in borate glasses

The g-factors expected for the various structures reported in borate glasses were calculated to predict the spectra observed in these glasses. The g-factors were calculated by DFT methods (ADF and G03w). Based on these calculations, the BOHC1 and BOHC2 were attributed to non-bridging oxygen bonded to threefold coordinated boron attached to a boroxol ring and an unpaired electron trapped by an orthoborate unit, respectively.