The multiple-quantum magic-angle spinning (MQMAS) experiment is a popular choice for obtaining high-resolution solid-state NMR spectra of quadrupolar nuclei with half-integer spin quantum number. However, its inherently poor sensitivity limits its application in more challenging systems. In particular, the use of higher-order multiple-quantum coherences, which have the potential to provide higher resolution in the isotropic spectrum, results in a further decrease in sensitivity. Here we extend our recent work, which introduced an automated, high-throughput approach to generate amplitude-modulated composite pulses (termed FAM-N) to improve the efficiency of the conversion of three-quantum coherences, and explore the use of similar pulses in five-quantum MAS experiments. We consider three different approaches, and are able to demonstrate that all three provide good enhancements over single pulse conversion in all but the most extreme cases, and work well at a range of spinning rates. We show that FAM-N pulses are robust to variation in the quadrupolar coupling and rf nutation rate, demonstrating their applicability in multisite systems and systems where direct experimental optimisation of complex composite pulses is not feasible. This work will ease the implementation of higher-order MQMAS experiments and enable their application to materials and systems that were previously deemed too difficult to study.

多量子魔术角旋转（MQMAS）实验是获得具有半整数自旋量子数的四极核的高分辨率固态NMR光谱的流行选择。但是，其固有的敏感性不足限制了其在更具挑战性的系统中的应用。特别是，使用具有在各向同性光谱中提供更高分辨率的潜力的高阶多量子相干会导致灵敏度进一步降低。在这里，我们扩展了我们最近的工作，该工作引入了一种自动化的高通量方法来生成振幅调制复合脉冲（称为FAM-N），以提高三量子相干转换的效率，并探索在模拟中使用类似脉冲的方法。五量子MAS实验。我们考虑三种不同的方法，并能够证明，除了最极端的情况以外，所有这三种方法都比单脉冲转换提供了更好的增强，并且在一定范围的旋转速度下都能很好地工作。我们表明，FAM-N脉冲对四极耦合和RF频率的变化具有鲁棒性，证明了它们在多站点系统和复杂复合脉冲的直接实验优化不可行的系统中的适用性。这项工作将简化高阶MQMAS实验的实施，并使它们能够应用于以前认为难以研究的材料和系统。证明了它们在多站点系统和复杂复合脉冲的直接实验优化不可行的系统中的适用性。这项工作将简化高阶MQMAS实验的实施，并使它们能够应用于以前认为难以研究的材料和系统。证明了它们在多站点系统和复杂复合脉冲的直接实验优化不可行的系统中的适用性。这项工作将简化高阶MQMAS实验的实施，并使它们能够应用于以前认为难以研究的材料和系统。