RELIABLE LOW-TEMPERATURE NMR SAMPLE CELL FOR REDUCED-GEOMETRY STUDIES

This paper reports an NMR sample cell and probe design suitable for hi gh sensitivity experimental studies, e.g. thin film studies of molecul ar hydrogen adsorbed on substrates such as hexagonal boron nitride. Ea sily machinable Kel-F (polychlorotrifluoroethylene or Fluorothene) is used in the NMR sample cell construction to fulfil two requirements: t he sample cell should be superfluid He-4 leak-tight and the material f or the sample cell should exhibit a minimal background proton NMR sign al. Using this new sample cell design, the signal from monolayer cover ages of molecular hydrogen containing 10(17) spins adsorbed on the hex agonal BN surface has been observed, with a signal-to-noise ratio > 10 0.