Due to their high gyromagnetic ratio, there is considerable interest in measuring distances and correlations involving protons, but such measurements are compounded by the simultaneous recoupling of chemical shift anisotropy (CSA). This secondary recoupling adds additional modulations to the signal intensities that ultimately lead to t₁-noise and signal decay. Recently, Venkatesh et al. demonstrated that the addition of CSA refocusing periods during ¹H-X dipolar recoupling led to sequences with far higher stability and performance. Herein, we describe a related effort and develop a symmetry-based recoupling sequence that continually refocuses the ¹H CSA. This sequence shows superior performance to the regular and t₁-noise eliminated D-HMQC sequences in the case of spin-1/2 nuclei and comparable performance to the later for half-integer quadrupoles.

由于它们的高旋磁比，人们对测量涉及质子的距离和相关性有相当大的兴趣，但这种测量因化学位移各向异性 (CSA) 的同时重新耦合而变得更加复杂。这种二次重新耦合对信号强度增加了额外的调制，最终导致t ₁噪声和信号衰减。最近，Venkatesh 等人。证明在¹ H-X 偶极重耦合期间添加 CSA 重聚焦周期会导致序列具有更高的稳定性和性能。在此，我们描述了一项相关工作并开发了一种基于对称的重新耦合序列，该序列不断重新聚焦¹ H CSA。此序列显示出优于常规和t _1的性能-在自旋 1/2 核的情况下，噪声消除了 D-HMQC 序列，并且对于半整数四极杆的性能与后者相当。