H-1-OVERHAUSER SHIFT IN RADICAL-CATION SALTS

Radical cation salts of planar aromatic pure hydrocarbons are model sy stems for quasi-one-dimensional organic conductors. The mobility of th e conduction electrons leads to a strong motional narrowing of the ele ctron spin resonance (ESR). These narrow lines allow detailed investig ations of the Overhauser shift of the ESR. This shift is caused by hyp erfine interaction of the conduction electrons with protons and C-13. By a double resonance technique this shift can be measured, and invest igations of NMR saturation and nuclear relaxation times are presented. The lineshape of the H-1-resonance is dominated by dipolar proton-pro ton coupling. We show that the Overhauser shift technique is similar t o common CW-NMR but with an improved sensitivity.