Near-forward Raman study of a phonon-polariton reinforcement regime in   the Zn(Se,S) alloy
  We investigate by near-forward Raman scattering a presumed reinforcement of the (A-C,B-C)-mixed phonon-polariton of a A1-xBxC zincblende alloy when entering its longitudinal optical (LO-)regime near the Brillouin zone centre {\Gamma}, as predicted within the formalism of the linear dielectric response. A choice system to address such issue is ZnSe0.68S0.32 due to the moderate dispersion of its refractive index in the visible range, a sine qua non condition to bring the phonon-polariton insight near {\Gamma}. The LO-regime is actually accessed by using the 633.0 nm laser excitation, testified by the strong emergence of the (Zn-Se,Zn-S)-mixed phonon-polariton at ultimately small scattering angles. 
Rami Hajj Hussein, Olivier Pag\`es, Franciszek Firszt, Agnieszka   Marasek, Wojtek Paszkowicz, Alain Maillard and Laurent Broch
cond-mat.mtrl-sci