Courtney Joseph M, Rienstra Chad M
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
J Magn Reson. 2016 Aug;269:152-156. doi: 10.1016/j.jmr.2016.05.016. Epub 2016 Jun 2.
We present a systematic study of dipolar double quantum (DQ) filtering in (13)C-labeled organic solids over a range of magic-angle spinning rates, using the SPC-n recoupling sequence element with a range of n symmetry values from 3 to 11. We find that efficient recoupling can be achieved for values n⩾7, provided that the (13)C nutation frequency is on the order of 100kHz or greater. The decoupling-field dependence was investigated and explicit heteronuclear decoupling interference conditions identified. The major determinant of DQ filtering efficiency is the decoupling interference between (13)C and (1)H fields. For (13)C nutation frequencies greater than 75kHz, optimal performance is observed without an applied (1)H field. At spinning rates exceeding 20kHz, symmetry conditions as low as n=3 were found to perform adequately.
我们利用具有从3到11的一系列n对称值的SPC-n重耦序列元件，在一系列魔角旋转速率下，对（13）C标记的有机固体中的偶极双量子（DQ）滤波进行了系统研究。我们发现，只要（13）C章动频率在100kHz或更高的量级上，对于n⩾7的值就可以实现有效的重耦。研究了解耦场依赖性，并确定了明确的异核解耦干扰条件。DQ滤波效率的主要决定因素是（13）C和（1）H场之间的解耦干扰。对于大于75kHz的（13）C章动频率，在没有施加（1）H场的情况下观察到最佳性能。在超过20kHz的旋转速率下，发现低至n = 3的对称条件也能充分发挥作用。
