The Raman Spectrum of Vinylidene Fluoride

The Raman spectrum of vinylidene fluoride has been obtained in the liquid state at −100 to −125°C. The observed frequencies were assigned to the fundamental modes of vibration (and several combinations of these) with the aid of the infra-red data in the literature supplemented by some measurements in our laboratory. A normal coordinate treatment of the vibrations has been carried out using a simple valency force field plus one additional term depending upon the square of the change in the F–F distance. It is shown that the repulsion between the F atoms and between each F atom and the π-electrons of the double bond are of major importance.