[Spectra analysis of [MnHg(SCN)4 (H2O)2 x 2C4H9NO (MMTWD) crystals]

The factor group symmetry analysis method was used to predict lattice vibrational modes of MMTWD single crystal, and it was found that there are no more than 297 and 148 theoretically observable Raman peaks and infrared reflection bands, respectively. The Raman and IR spectra were measured at room temperature. All the Raman and IR spectra peaks were assigned on the basis of the group theory and lattice dynamics theory. According to the Raman and IR spectra, the molecular structure of MMTWD crystal was discussed. From the results of the present theoretical and experimental works, the three-dimensional network structure of MMTWD crystal was identified. This structure provides the crystal with a large interaction force between molecules, which in turn induces high stability and macroscopic nonlinear optical properties.