THE VIBRATIONAL-SPECTRA OF PBMG(CO3)(2)

The vibrational spectra of synthetic PbMg(CO3)(2) are measured at ambi ent temperature and atmospheric pressure by FTIR and Raman spectroscop y. A number of first-order internal modes of the carbonate ion group a re found to be infrared (nu(2), nu(3), nu(4)) and Raman (nu(1), nu 2, nu(3), nu(4)) active. Additionally, the (nu 1 + nu 3) and (nu 1 + nu 4 ) combination modes are observed in the FTIR spectrum. The carbon isot opic-shift coefficient for nu 2 due to the substitution of C-12 by C-1 3 (nu 2((CO32-)-C-13)/nu 2((CO32-)-C-12)=0.967+/-0.003) agrees with th e theoretical value of 0.969.