Complete spectrum of long-wavelength phonon modes in Sn2P2S6 by Raman scattering -: art. no. 064308

The paper presents polarized Raman spectra of Sn2P2S6 measured in various backscattering and near-forward and right-angle scattering geometries at T = 15 K. The complete sets of AT'(TO), A(X)', A(Z)', AT(TO), and A(LO) mode frequencies are determined. The essential problem of symmetry assignment was solved with the help of measurements of directional dependencies of the oblique mode frequencies.