Cyclic and Slice-Selective J Cross Polarization for Heteronuclear Editing and Localized NMR

Abstract

This work has two objectives. First, heteronuclear editing was considered, with particular aim at proton-detected NMR spectroscopy of rare nuclei. The second aspect refers to localized heteronuclear NMR spectroscopy, implying the editing option. The common basis of both techniques is J cross polarization (or coherent rotating-frame polarization transfer). In the presence of magnetic field gradients this process is slice selective and is introduced as a principle for localized liquid-state NMR, particularly of heteronuclear spins. Heteronuclear editing of NMR lines is performed by the aid of a cyclic cross-polarization pathway. Both methods can be combined to a technique for localized proton-detected NMR spectroscopy of rare nuclei. Test experiments demonstrating the slice selectivity of the transfer process and the efficiency of the cyclic cross-polarization editing procedure are reported. Applications to localized homo- or heteronuclear spectroscopy and imaging are discussed.