CDW evidence in one-dimensional K0.3MoO3 by means of Raman scattering

Raman scattering measurements on the one-dimensional (1-D) blue bronze K_0.3MoO₃ are reported as function of temperature. At about 50 cm^-1 a Raman line of A_g(A) symmetry was found with an anomalous temperature dependence. The line symmetry, the softening of the eigenfrequency and the apparent disappearing of the coupling constant at the critical temperature, allow us to assign this line to the amplitude mode of the CDW, predicted by the theory of the Peierls transition. A Peierls precursor at room temperature was also observed and is discussed.