Electronic structure, optical properties and lattice dynamics of MgSO3⋅6H2O

The electronic band structure, optical properties and lattice vibrations of MgSO3⋅6H2O were studied within density functional theory and compared to the experimental optical data and polarized Raman spectra. Due to the 'molecular' nature of the MgSO3⋅6H2O crystal all Γ-point phonon modes could be separated into groups belonging to specific structural blocks: Mg(H2O)6 octahedra, SO3 units and H2O molecules. All Raman lines in the experimental spectra are assigned to definite vibrations of the structure and reasonable agreement is found between theoretical and experimental mode frequencies. The temperature-dependent Raman spectra reveal at 60 °C a sharp transition from MgSO3⋅6H2O to anhydrous amorphous MgSO3 without the noticeable presence of intermediate lower hydrates, such as MgSO3⋅3H2O. (paper)