MAGNETIC-SUSCEPTIBILITY OF ONE-DIMENSIONAL METALLIC CHAINS IN SOLUTION

We report the results of electron spin resonance (ESR) measurements of the magnetic susceptibility (χ) of polyaniline in solution in concentrated sulfuric acid and at low temperatures in the matrix of the frozen glass. The results indicate that in solution, the magnetic susceptibility is decreased with respect to χ in the solid state by more than two orders of magnitude. Since dissolution weakens the interchain coupling while leaving the macromolecular chains intact, polyaniline chains in sulfuric acid can be considered as one-dimensional (1d) metals. Accordingly, we have interpreted the decrease in χ as arising from the Peierls' instability; the 1d metallic chains distort to form a superlattice with an associated energy gap in the excitation spectrum. © 1990.