A polarized infrared and Raman spectroscopic study of the electrooptic crystalm-nitroaniline. 2—lattice vibrations

The polarized Raman spectra of meta-nitroaniline single crystals in the 10–150 cm−1 region as well as the far-infrared spectra of the (010) platelets in the 20–200 cm−1 region have been measured and assignments of all expected bands have been proposed on the basis of the observed polarizations. To estimate the influence of the electrooptical properties of the crystal on the lattice spectra, the relative intensities of librational bands have been calculated from the oriented gas model, and observed discrepancies have been discussed. Comparisons with the spectra of the isomeric crystal p-nitroaniline and of a similar non-centrosymmetric crystal m-chloronitrobenzene have been made.