Direct evidence of a magnetization transfer between laser-polarized xenon and protons of a cage-molecule in water

In a dedicated experimental setup, we directly prepare liquid-state NMR sam ples containing laser-polarized xenon with nuclear polarization larger than 5% at pressures up to 4 bars. Coating of the NMR tube surface allows us to increase the self-relaxation time of xenon in the gaseous phase to approxi mately 4.5 hours. Using a modified SPINOE pulse sequence, we present the fi rst direct detection of a regioselective proton signal enhancement of a mol ecule (alpha -cyclodextrin) dissolved in water resulting from cross-polariz ation between laser-polarized xenon and protons.