Crystal Field Splitting in Raman Spectra of Polytetrafluoroethylene

Crystal field splitting of Raman-active line group fundamentals has been observed for the crystalline phase of polytetrafluoroethylene found at temperature below 19°C. At − 180°C Raman lines near 575 and 1215 cm−1 are split into components separated by 3.5 and 4.4 cm−1, respectively. Splitting of the Raman line near 385 cm−1 increases from 5.2 cm−1 at 0°C to 6.4 cm−1 at − 180°C, indicating increasing intermolecular interaction with decreasing temperature. It is suggested that the space group of this phase is P21 and that the unit cell has dimensions a = 5.59 Å, b = 9.76 Å, c = 16.88 Å with β = 90° and contains two molecules.