N-Type Doping of Polyacetylene ESR Study Versus Temperature

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Abstract
We have studied the evolution with temperature 30C K≤ T ≤ 500 K of the ESR charaeteristics, on Lithium doped cis-polyacetylene films (using metal complexes of Benzophenone or Naphthalene in THP). Asymmetric ESR lines were observed at R T for samples doped at ∼4% and ∼l6%. Annealing of the doped samples up to 500 K results in a significant irreversible increase of the peak to peak linewidth δpp at RT, while the asymmetry ratio A/B increases irreversiblyonly in the case of samples doped at-4%. Nevertheless for temperatures above 400 K a narrow ESR line (δpp < 1G) superposed on the asymmetric broader line was observed. In order to interpret these temperature behaviors, we suggest a model which takes into account the inhomogeneity of the dopant distribution and the solvent influence.