Removing the Dipolar Interaction Between the Nuclear Spins caused by the Lee-Goldburg Pulse in Solid Hetero-Correlation NMR Spectroscopy

摘要

In nuclear magnetic resonance (NMR), the interaction Hamiltonian for the spin system, which governs the dynamics of spin coherence, can be modified by using strong radio-frequency (r f) pulses. Among several possibilities, the Lee-Goldburg (LG) off resonance scheme is adopted in removing the homo-dipolar interaction. In this report, the LG scheme is analyzed theoretically with the density operator formalism. A pulse sequence of our own is written and tested with monoethyl-fumerate. The LG scheme is also used for a selective cross-polarization between C-13 and H-1, where the spin diffusion among H-1 is suppressed while the cross talk between (1)Hand C-13 is maintained. The spin diffusion between H-1 and C-13 is increased for longer cross polarization times, which is verified by the emergence of new correlation peaks. This technique should be useful in analyzing the molecular structures of solid materials such as nano powders.