Walls Jamie D, Lin Yung-Ya
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Solid State Nucl Magn Reson. 2006 Feb;29(1-3):22-9. doi: 10.1016/j.ssnmr.2005.09.007. Epub 2005 Oct 28.
We present a general method for constructing a subset of the constants of motion in terms of products of spin operators. These operators are then used to give insight into the multi-spin orders comprising the quasi-equilibrium state formed under a Jeener-Broekaert sequence in small, dipolar-coupled, spin systems. We further show that constants of motion that represent single-quantum coherences are present due to the symmetry of the dipolar Hamiltonian under 180 degrees spin rotations, and that such coherences contribute a DC component to the FID which vanishes in the absence of the flip-flop terms and is only present for spin clusters with an odd number of spins.
我们提出了一种基于自旋算符乘积构建运动常数子集的通用方法。然后，这些算符被用于深入了解由小的、偶极耦合的自旋系统在耶纳 - 布勒卡特序列下形成的准平衡态所包含的多自旋序。我们进一步表明，由于偶极哈密顿量在180度自旋旋转下的对称性，存在代表单量子相干性的运动常数，并且这种相干性会给自由感应衰减（FID）贡献一个直流分量，该分量在没有翻转项时消失，并且仅在具有奇数个自旋的自旋簇中存在。
