Raman Spectrum of Semiconducting and Metallic VO2

The Raman scattering spectrum of V${\mathrm{O}}_2$ is reported between 4.2 and 600°K. In the semiconducting monoclinic phase only sharp phonon structure is observed. The metallic rutile phase exhibits a pronounced softening and damping in the observed phonon spectrum. This evidence supports a recently proposed phenomenological mechanism for the semiconductor-to-metal transition.