Robust and efficient 19F heteronuclear dipolar decoupling using refocused continuous-wave rf irradiation.

摘要: Abstract Refocused continuous wave (rCW) decoupling is presented as an efficient and robust means to obtain well-resolved magic-angle-spinning solid-state NMR spectra of low-γ spins, such 13C dipolar coupled fluorine. The rCW sequences, recently introduced for 1H decoupling, are very towards large isotropic anisotropic shift ranges often encountered 19F spins. In the so-called refocusing pulses inserted into CW irradiation eliminate critical residual second- third-order coupling dipolar-coupling against chemical shielding anisotropy cross-terms in effective Hamiltonian through time-reversal (i.e. refocusing). As important additional assets, sequences variations rf amplitudes, operational at low high spinning speeds, easy set-up optimal performance experimentally. These aspects demonstrated analytically/numerically experimentally comparison state-of-the-art TPPM, SPINAL-64, frequency-swept variants these.