Methods for Heteronuclear Thin-Film NMR

The fabrication and analysis of¹⁹F-based and¹H-based thin films and the NMR techniques employed for studying them are discussed. The heteronuclear magnetization transfer results in disordered media that motivated the development of the ordered thin-film techniques are summarized. The experimental setup and sample geometry for the thin-film experiments are described, and the techniques for thin-film preparation and thickness measurement are discussed. For the NMR spectrometer, coil tuning via changing the applied magnetic field and the techniques employed for lowering the dead time are described. No signal averaging was required to obtain spin echoes from a sample composed of 0.5 μm thin films.T₁values on the order of one minute were measured in the thin films at a temperature of 0.5 K. These techniques should be of particular use in studying cross relaxation at surfaces and NMR of membrane proteins.