EPR study of chemically synthesized polypyrroles soluble in organic solvents

The results of electron paramagnetic resonance (EPR) experiments are report ed for chemically synthesized polypyrroles soluble in organic solvents, whi ch have different doping levels. Pauli susceptibility (chi(P)) and the dens ity of states [D(E-F)] are obtained from the temperature dependence of magn etic susceptibility. The XP and the D(E-F) increase as the doping level inc reases, which indicates that the system becomes more highly conducting. The electron spin-lattice relaxation time (T-1) is measured by using saturatio n methods. The T-1 decreases with increasing doping level at room temperatu re. This implies that the spin-lattice interaction easily occurs in the sam ple with the high concentration of dopants. The EPR linewidth (Delta H) lin early increases as temperature increases from 100 K to room temperature. We use a Korringa relaxation rate to account for the temperature dependence o f the Delta H. [S0163-1829(99)04809-2].