Raman investigation of the charge-density-wave mixed-crystal system1T−TaS2−xSex

The results of Raman scattering measurements on the mixed-crystal system $1T-\mathrm{T}\mathrm{a}{\mathrm{S}}_{2-x}{\mathrm{Se}}_x$ in the commensurate charge-density-wave state are reported. In the pure compounds, our measurements indicate that a strong LA-TA phonon interaction at the distortion wave-vector results in additional coupled charge-density-wave-lattice excitations. These excitations can be followed over the whole range of concentrations in the mixed crystals. The concentration dependences of the mode frequencies are treated using an effective oscillator model.