Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
J Magn Reson. 2011 Sep;212(1):234-9. doi: 10.1016/j.jmr.2011.06.013. Epub 2011 Jul 20.
A train of short rotor-synchronized pulses in the manner of Delays Alternating with Nutations for Tailored Excitation (DANTE) applied to nitrogen-14 nuclei (I=1) in samples spinning at the magic angle at high frequencies (typically νrot=62.5 kHz so that τrot=16 μs) allows one to achieve uniform excitation of a great number of spinning sidebands that arise from large first-order quadrupole interactions, as occur for aromatic nitrogen-14 nuclei in histidine. With routine rf amplitudes ω1(14N)/(2π)=60 kHz and very short pulses of a typical duration 0.5<τp<2 μs, efficient excitation can be achieved with 13 rotor-synchronized pulses in 13 τrot=208 μs. Alternatively, with 'overtone' DANTE sequences using 2, 4, or 8 pulses per rotor period one can achieve efficient broadband excitation in fewer rotor periods, typically 2-4 τrot. These principles can be combined with the indirect detection of 14N nuclei via spy nuclei with S=½ such as 1H or 13C in the manner of Dipolar Heteronuclear Multiple-Quantum Correlation (D-HMQC).
采用以交替延迟进动为特征的定制激发（DANTE）方式施加于在高频下以魔角旋转（通常 νrot=62.5 kHz，从而 τrot=16 μs）的样品中的氮-14 核（I=1）的短转子同步脉冲序列，可以实现对大量由大一级四极相互作用引起的旋转边带的均匀激发，这种情况发生在组氨酸中的芳香氮-14 核上。在常规射频幅度 ω1(14N)/(2π)=60 kHz 和典型持续时间 0.5<τp<2 μs 的非常短脉冲下，可以用 13 个 τrot=208 μs 的转子同步脉冲实现有效的激发。或者，使用每个转子周期 2、4 或 8 个脉冲的“倍频”DANTE 序列，可以在更少的转子周期内实现有效的宽带激发，通常为 2-4 τrot。这些原理可以与通过具有 S=½ 的间谍核（例如 1H 或 13C）间接检测 14N 核的方式（如双共振异核多量子相关（D-HMQC））相结合。
