Raman scattering in single-crystalline CuO samples has been studied. From the polarization dependence, the symmetries of the three Raman-active optical phonons have been identified. The ${\mathit{A}}_{\mathit{g}}$ Raman mode with frequency of 290 ${\mathrm{cm}}^{\mathrm{-}1}$ was found to be strongly polarized along one of the crystal axes. This suggests that there are cancellations between different components of its Raman tensor.

• Received 11 December 1989

DOI:https://doi.org/10.1103/PhysRevB.41.7192