From Short-Range to Long-Range Intermoleeular NOEs in Ionic Liquids: Frequency Does Matter

摘要

The nuclear Overhauser effect (NOE) is widely used for studying local structures in liquids and solutions. The NOE reflects cross-relaxation between two nuclear spins, I and S, because of magnetization transfer through coupling of their magnetic dipole moments. With increasing internuclear distance r the cross-relaxation rate σ_(IS) decays as 1/r~6. Thus, a NOE is only achieved, if r is less than 4—5 A.