ESR Study of Metallic Complexes of Alkali-Doped Polyacetylene
We have followed the dependence of ESR linewidth (ΔH ) of highly alkali-metal doped polyacetylene on the nature of the dopant and on the temperature in the range from 4 K to 300 K. The room-temperature linewidth increases with increasing atomic number (z) of the dopant and seems to follow a zα-law with a ≃ 2.3 ± 0.7 which is close to the z4 law expected for metals. This linewidth behaviour suggests a significant contribution from the spin-orbit coupling of the unpaired electrons on the dopant site. Thus, according to Elliott’s model, we have been able, in the case of Li-, K-and CS-doped films, to estimate the expected electronic g-factor deviations from the free-electron g-value. The linewidth decreases quasi-linearly with decreasing temperature down to ∽80 K where it starts to increase. This temperature behaviour can be analyzed in terms of gradual transition from delocalized states at high temperature, where interchain electron hopping plays a dominant role, to localized states at low temperature where electrons are mainly confined along the chains.
KeywordsDopant Atom Metallic Complex Dopant Site Naphthalene Complex Longitudinal Scattering
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