Overhauser shift of the electron spin resonance in the conducting form of polythiophene

Abstract

The Overhauser shift Δ B ov (ν p) of the electron spin resonance line due to dynamic nuclear spin polarization (DNP) of the hyperfine coupled nuclei is observed for the fully doped, conducting form of polythiophene at 1.9 K. The DNP enhancement factor V ≈ 55 is determined via dependence of the Δ B ov (ν p) on the microwave power. The proton spin relaxation time T H 1 = 1.47 s at 1.9 K was determined from the relaxation of the Δ B ov (ν p) after switching off the rf pulse. A total average hyperfine coupling NA zz = −5.6 MHz of the protons corresponding to a spin density of ϱ π CH ≈ 8.7 × 10 −2/ N was determined from Δ B ov (ν p).