In MQMAS-based high-resolution solid-state NMR experiments of half-integer spin quadrupolar nuclei, the high radiofrequency (RF) field requirement for the MQ excitation and conversion steps with two hard-pulses is often a sensitivity limiting factor in many practical applications. Recently, the use of two cosine-modulated (cos) low-power (lp) pulses, lasting one-rotor period each, was successfully introduced for efficient MQ excitation and conversion of spin-3/2 nuclei with a reduced RF amplitude. In this study, we extend our previous investigations of spin-3/2 nuclei to systems with higher spin values and discuss the applicability of coslp-MQ excitation and conversion in MQMAS and MQ-HETCOR experiments under slow and fast spinning conditions. For the numerical simulations and experiments we used a moderate magnetic field of 14.1 T. Two spin-5/2 nuclei (⁸⁵Rb and ²⁷Al) are mainly employed with a large variety of C_Q values, but we show that the practical set up is also available for higher spin values, such as spin-9/2 with ⁹³Nb in Cs₄Nb₁₁O₃₀. We demonstrate for nuclei with spin value larger than 3/2 a preferential use of coslp-MQ acquisition for low-gamma nuclei and/or large C_Q values with a much reduced RF-field with respect to that of hard-pulses used with conventional methods.

在基于 MQMAS 的半整数自旋四极核的高分辨率固态 NMR 实验中，具有两个硬脉冲的 MQ 激发和转换步骤的高射频 (RF) 场要求通常是许多实际应用中的灵敏度限制因素. 最近，成功引入了两个余弦调制 (cos) 低功率 (lp) 脉冲，每个脉冲持续一个转子周期，以实现高效的 MQ 激发和自旋 3/2 核的转换，同时降低 RF 振幅。在这项研究中，我们将之前对自旋 3/2 核的研究扩展到具有更高自旋值的系统，并讨论了 coslp-MQ 激发和转换在MQMAS 和 MQ-HETCOR 在慢速和快速旋转条件下进行的实验。对于数值模拟和实验，我们使用了 14.1 T 的中等磁场。两个自旋 5/2 原子核（⁸⁵ Rb 和²⁷ Al）主要用于各种 C _Q值，但我们表明实际设置也可用于更高的自旋值，例如Cs ₄ Nb ₁₁ O _30中具有⁹³ Nb 的 spin-9/2 。我们展示了对于自旋值大于 3/2 的原子核，优先使用 coslp-MQ 采集低伽马原子核和/或大 C _Q值，相对于常规使用的硬脉冲，RF 场大大减少方法。