Rodin Bogdan A, Kiryutin Alexey S, Yurkovskaya Alexandra V, Ivanov Konstantin L, Yamamoto Satoru, Sato Kazunobu, Takui Takeji
International Tomography Center SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia.
International Tomography Center SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia.
J Magn Reson. 2018 Jun;291:14-22. doi: 10.1016/j.jmr.2018.03.005. Epub 2018 Mar 27.
A method is proposed for optimizing the performance of the APSOC (Adiabatic-Passage Spin Order Conversion) technique, which can be exploited in NMR experiments with singlet spin states. In this technique magnetization-to-singlet conversion (and singlet-to-magnetization conversion) is performed by using adiabatically ramped RF-fields. Optimization utilizes the GRAPE (Gradient Ascent Pulse Engineering) approach, in which for a fixed search area we assume monotonicity to the envelope of the RF-field. Such an approach allows one to achieve much better performance for APSOC; consequently, the efficiency of magnetization-to-singlet conversion is greatly improved as compared to simple model RF-ramps, e.g., linear ramps. We also demonstrate that the optimization method is reasonably robust to possible inaccuracies in determining NMR parameters of the spin system under study and also in setting the RF-field parameters. The present approach can be exploited in other NMR and EPR applications using adiabatic switching of spin Hamiltonians.
提出了一种优化绝热通道自旋序转换（APSOC）技术性能的方法，该技术可用于单重态自旋态的核磁共振实验。在该技术中，通过使用绝热斜坡射频场来实现磁化到单重态的转换（以及单重态到磁化的转换）。优化采用了梯度上升脉冲工程（GRAPE）方法，在该方法中，对于固定的搜索区域，我们假设射频场的包络具有单调性。这种方法能够使APSOC实现更好的性能；因此，与简单的模型射频斜坡（如线性斜坡）相比，磁化到单重态的转换效率得到了极大提高。我们还证明，该优化方法对于所研究自旋系统的核磁共振参数测定以及射频场参数设置中可能存在的不准确之处具有合理的鲁棒性。本方法可用于其他使用自旋哈密顿量绝热切换的核磁共振和电子顺磁共振应用中。
