A laser Raman study of the stress dependence of vibrational frequencies of a monocrystalline polydiacetylene

摘要: The applicaiton of a tensile stress to monocrystalline fiber polydiacetylene, an extended‐chain polymer, causes the Raman‐observed C≡C and C=C in‐chain vibrational frequencies decrease linearly with elongation. polymer studied, poly‐HDU, results from solid state polymerization R–C≡C–C≡C–R, where R=–CH2OCONHC6H5. This experimental relationship between bond frequency shifts deformation is analyzed by calculating force constant changes as function macroscopic stress. It shown that possible effects due stress‐induced in electron delocalization this fully conjugated are negligible principal contributions anharmonicity. Models which assume entire effect anharmonicity produce calculated dependencies ν (C=C) (C≡C) upon fractional elongation, good agreement observed.