An optimized pulse sequence for the spectrally selective reintroduction of heteronuclear dipole-dipole interactions (frequency-selective dipolar recoupling) into solid state magic angle spinning (MAS) NMR experiments on polycrystalline samples has been studied. In the simple peptide glycylglycine, the selective dipolar evolution of two spins is observed while the influence of a larger internuclear coupling is suppressed. This approach is aimed at obtaining several quantitative internuclear distances simultaneously in dipolar recoupling MAS experiments by reducing multiple spin effects in observed dipolar evolution. In addition, the incoherent influences on heteronuclear dipolar evolution are treated using a simple computational approach within an exponential model. A similar frequency-selective experiment for transferring polarization is also introduced, and an analogous dephasing experiment for non-spinning solids is presented.
NIH ExPorter
NIH ExPorter