Annabestani Razieh, Cory David G
1Institute for Quantum Computing, University of Waterloo, Waterloo, ON N2L 3G1 Canada.
2Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 Canada.
Quantum Inf Process. 2018;17(1):15. doi: 10.1007/s11128-017-1777-6. Epub 2017 Dec 9.
We analyze the symmetry properties of the dipolar Hamiltonian as the main relaxation mechanism responsible for the observed NMR spectra of long-lived states of methyl groups. Long-lived states exhibit relaxation times that are considerably longer than the spin-lattice relaxation time, . The analysis is complementary to previous studies and provides insight into the relaxation mechanism of long-lived states by focusing exclusively on the symmetry of the spin Hamiltonian. Our study shows that the dipole-dipole coupling between protons of a methyl group and between the protons and an external spin are both symmetry breaking interactions that can lead to relaxation pathways that transform the polarization from symmetry order to Zeeman order. The net contribution of the internal dipolar interaction to the NMR observation of long-lived states is zero. Our calculation is in good agreement with the reported features of the observed spectra and previous theoretical studies.
我们分析了偶极哈密顿量的对称性性质，它是导致甲基长寿命态观测到的核磁共振谱的主要弛豫机制。长寿命态的弛豫时间比自旋 - 晶格弛豫时间长得多。该分析是对先前研究的补充，通过专门关注自旋哈密顿量的对称性，深入了解长寿命态的弛豫机制。我们的研究表明，甲基质子之间以及质子与外部自旋之间的偶极 - 偶极耦合都是对称性破缺相互作用，它们可导致将极化从对称序转变为塞曼序的弛豫途径。内部偶极相互作用对长寿命态核磁共振观测的净贡献为零。我们的计算与观测光谱的报道特征以及先前的理论研究结果吻合良好。
