Moderate MAS enhances local (1)H spin exchange and spin diffusion.

摘要: Proton NMR spin-diffusion experiments are often combined with magic-angle spinning (MAS) to achieve higher spectral resolution of solid samples. Here we show that local proton spin diffusion can indeed become faster at low (<10 kHz) rates as compared static conditions. Spin under conditions thus be slower than the referred value 0.8 nm(2)/ms, which was determined using slow MAS (Clauss et al., 1993). The enhancement by relies on modulation orientation-dependent dipolar couplings during sample rotation and goes along transient level crossings in combination truncation. experimental finding its explanation is supported density matrix simulations, also emphasizes sensitivity coupling topology. amplification cannot explained any model based independent pairs; least three spins have considered.