Isomerization and Spin Generation in Polyacetylene

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Abstract
The isomerization of undoped (CH)x was investigated in a combined Raman and ESR experiment. We find that the ESR linewidth, but not the spin concentration, is correlated with the degree of isomerization as determined from the Raman intensities. The spin concentratin does not change until the isomerization is well change untill the isomerization is well advanced. Hence the decrease in linewidth must be due to the increased mobility of the spins (solitons) rather than exchange interaction. The Spin qeneration is suggested to be due to Diels-Alder crosslinking. The Raman intensities indicate that there are two isomerization processes, with activation energies of 16 and 28 kcal/mole. Anomalous Raman scattering by cis (CH)x excited with de ep red laser light provides additional evidence for defect structures.