Heteronuclear decoupling under fast MAS by a rotor-synchronized Hahn-echo pulse train

• DOI: 10.1016/j.jmr.2005.06.007
• Publication Date: 2005-07-22T16:04:42Z
• Authors: Xenia Filip; Carmen Tripon; Claudiu Filip
• Keywords: Models, Chemical; Computer Simulation; Signal Processing, Computer-Assisted; Spin Labels; Protons; Nuclear Magnetic Resonance, Biomolecular; 01 natural sciences; 7. Clean energy; Algorithms; 0104 chemical sciences

A new heteronuclear decoupling mechanism under fast magic-angle spinning MAS is introduced. It is based on refocusing the coherences responsible for the dephase of low-gamma nuclei ((13)C, (15)N) transverse spin-polarization in the presence of strongly dipolar-coupled protons, and has the advantage that can be implemented by pulsed techniques, with all the benefits resulting from a reduced duty cycle compared with conventional decoupling by continuous rf irradiation. The decoupling efficiency of a simple rotor-synchronized Hahn-echo pulse train is analyzed both theoretically and experimentally. It was found that a substantial improvement in sensitivity and resolution can be achieved in compounds with small (1)H chemical shielding parameters even at moderate sample spinning, and some interesting applications are shown. It is also shown that much faster spinning frequencies, or alternative refocusing sequences, are needed for applications on rigid organic solids, i.e., in systems with larger (1)H chemical shifts.