Solitons in Polyacetylene: Magnetic Susceptibility

The absoulte spin susceptibility of As${\mathrm{F}}_5$-doped trans-polyacetylene, ${\left[\mathrm{CH}{\left(\mathrm{As}{\mathrm{F}}_5\right)}_y\right]}_x$, was determined by spin resonance techniques for $0.0004<~y<~0.138$. The Curie-law contribution decreases above $y=0.001\mathrm{}$ to a level less than 1 ppm in the highly conducting regime. The temperature-independent Pauli term is small (≤5×${10}^{-8\mathrm{}}$ emu/mole) for $y<\mathrm{}0.01\mathrm{}$, remains small up to $y=0.05\mathrm{}$, and shows an abrupt increase near $y=0.07\mathrm{}$ to a value of ∼ 3 × ${10}^{-6\mathrm{}}$ emu/mole at higher concentrations. The results are consistent with the soliton doping mechanism.