MOSSBAUER STUDIES OF THE VIBRATIONAL DYNAMICS OF GLASSY-POLYMERS CONTAINING FERROCENE

Mossbauer studies of glassy polymes containing ferrocene between 4.2 K and 300 K reveal low-temperature as well as high-temperature anharmonicities of the intermolecular vibrations. We interprete the low-temperature anharmonicity by plateaus of the intermolecular potentials with diameters of about 0.05 angstrom around the ferrocene units due to the free volume. The mean vibrational frequencies as well as the onset temperature of the high-temperature anharmonicity of about 200 K are independent of the position of the ferrocene unit relative to the chain. We conclude that the vibrational amplitude of this unit is determined by the movement of the chain itself. The analysis of the Goldanskii-Karyagin-effect reveals that the anharmonic softening is mainly perpendicular to the local chain axis. For ferrocene at chain ends the intermolecular forces are considerably smaller than at any other position along the chain.