Evidence for Soliton-Phonon Interaction in trans-Polyacetylene: Temperature and Frequency Dependence of Electron Spin-Lattice Relaxation Data

摘要

The temperature, frequency, and isotope dependence of the electron spin-lattice relaxation rate R sub 1 for the paramagnetic defects in pristine trans-polyacetylene is analyzed in terms of a model in which the electron-electron dipolar interaction between spins is modulated by one-dimensional diffusion induced by phonon scattering of the mobile spins. At room temperature, this model predicts a T to the 1/2 power temperature dependence for R sub 1; at low temperatures, depending upon assumptions about the phonon spectrum estimates on the temperature dependence of R sub 1 range from T squared to T to the 5/2 power. The frequency dependence of R sub 1 is theoretically predicted to be described by a angular frequency to the-1/2 power dependence which is found to accurately fit the experimental data obtained over the frequency range 35 MHz to 40 GHz. The interpretation of electron spin-lattice relaxation data is consistent with ENDOR, electron phase memory relaxation data, EPR line-width data, and nuclear relaxation data. We consider the implications of this analysis for various soliton descriptions of the paramagnetic defect.