VIBRATIONAL SPECTRAL STUDIES OF SOLUTIONS AT ELEVATED-TEMPERATURES AND PRESSURES .4. RAMAN-SPECTRA OF AQUEOUS ZINC NITRATE SOLUTIONS

Raman spectra of 5. 196 m aqueous zinc nitrate solution have been measured at a pressure of 11 MPa and temperatures ranging from 25 to 300 degree C. A band at 386 cm** minus **1, assigned to the hexaaquazinc(II) cation, decreases in intensity and increases in frequency as the temperature rises. These observations are consistent with the replacement of water molecules in the primary solvation shell of Zn**2** plus by a nitrate ion. Changes in the spectrum of nitrate ion support this interpretation. Evidence is also presented which suggests that the octahedral configuration around Zn**2** plus is being changed to a tetrahedral configuration.