Raman scattering and infrared reflectivity in GeSe

Raman and infrared-active zone-center optical phonon frequencies and dielectric constants of single-crystal, orthorhombic, germanium selenide (GeSe) are reported. The number of phonons observed for given polarization configurations is consistent with group-theoretical predictions. The near-degeneracy of some Raman and infrared modes suggests a dominance of intra-layer, compared to inter-layer, forces characteristic of "layer-type" compounds.