Paramagnetism and electron spin-lattice relaxation in thermolyzed polyphenylacetylene☆

Abstract The EPR spectrum of thermolyzed polyphenylacetylene (PPA) is analysed. In the case of low power levels the shape of the EPR spectrum is attributed to the presence of paramagnetic centres localized on structurally different segments of the PPA molecule. Experiments showed the linear dependence of the electron spin-lattice relaxation time T 1 in the temperature range 3–66°K. The experimental values of T 1 are of the same order of magnitude as the calculated values.