In solid-state NMR, multiple-quantum MAS (MQMAS) and satellite-transition MAS (STMAS) experiments are well-established techniques to obtain high-resolution spectra of half-integer quadrupolar nuclei. In 2004 and 2005, a soft-pulse-added-mixing (SPAM) concept was introduced by Gan and Amoureux to enhance the S/N ratio of MQMAS and STMAS experiments. Despite their robustness and simplicity, SPAM approaches have not yet been widely applied. Here, we further exploit SPAM concepts for sensitivity enhancement upon acquisition of two-dimensional MQMAS and STMAS spectra and also establish a general procedure upon implementation of SPAM-MQMAS and SPAM-STMAS NMR. Its effectiveness and ease in experimental setup are demonstrated using simulations and experiments performed on I ​= ​3/2 (²³Na, ⁸⁷Rb), 5/2 (²⁷Al, ⁸⁵Rb) and 9/2 (⁹³Nb) nuclei with a variety of quadrupolar coupling constants (C_Q). Compared to the conventional z-filter methods, sensitivity enhancements in between 2 and 4 are achievable with SPAM. We recommend to use SPAM with a ratio of 4:1 for the number of echoes and antiechoes to safely maximize the sensitivity and resolution simultaneously. In addition, a comparison of the experimental approaches is made in the context of SPAM-MQMAS and SPAM-STMAS NMR with respect to repetition delay and spinning frequency, aiming to discuss the precautions upon making a judicious choice of high-resolution NMR methods of half-integer quadrupolar nuclei.

在固态NMR中，多量子MAS（MQMAS）和卫星跃迁MAS（STMAS）实验是获得半整数四极核高分辨率光谱的成熟技术。在2004年和2005年，Gan和Amoureux引入了软脉冲混合技术（SPAM），以提高MQMAS和STMAS实验的信噪比。尽管具有鲁棒性和简便性，SPAM方法尚未得到广泛应用。在这里，我们进一步利用SPAM概念来提高二维MQMAS和STMAS光谱的灵敏度，并在实施SPAM-MQMAS和SPAM-STMAS NMR时建立通用程序。通过模拟和在I = 3/2（²³ Na，⁸⁷Rb），5/2（²⁷ Al，⁸⁵ Rb）和9/2（⁹³ Nb）原子核，具有各种四极耦合常数（C _Q）。与传统的z滤波器方法相比，SPAM可使灵敏度提高2到4之间。我们建议对回波和抗回波使用比例为4：1的SPAM，以安全地同时提高灵敏度和分辨率。另外，在SPAM-MQMAS和SPAM-STMAS NMR的背景下，就重复延迟和旋转频率进行了实验方法的比较，旨在讨论谨慎选择高分辨核磁共振方法的注意事项。 -整数四极核。