THE VIBRATIONAL-SPECTRA AND STRUCTURE OF NORDENSKIOLDINE

We report the infrared and Raman spectra of nordenskioldine. Bands in the spectra of nordenskioldine are assigned to the corresponding vibrational modes by a calculation of normal modes within the all-valence force-field model and by a comparison with calculated and measured results for the isostructural dolomite, The characteristic double peaks for the out-of-plane bending mode v2 and the asymmetric stretching mode v3 of the BO33- group are attributed to the substitution effect of B-11 and B-10 in nordenskioldine. The calculated intensities in the Raman spectra for nordenskioldine and dolomite are related to the differences in electric dipole polarizabilities and to the electronic structure for BO33- and CO32- groups, consistent with the first-principles calculations.