时间标签：数据日期 2026-10-31 · 生成时间 2026-11-01 05:30（Asia/Shanghai）｜ 检索窗口 PubMed edat 2026/10/28–2026/10/31 ｜ 情报发生日期 2026-10-31
研究问题
Although LLSs and LLCs have been observed experimentally in methylene networks, their origin and general structure in chains of arbitrary length have remained unclear.；Here we show that these relaxation-protected modes follow directly from Redfield relaxation theory.；However, the origin of these delocalized LLSs and col- lective LLCs in multi-spin chains is less evident than in the two-spin case.
方法
We further develop a general framework for constructing both LLSs and LLCs in aliphatic chains containing an arbitrary number of −CH2− groups in achiral molecules, and illustrate the approach explicitly for chains with N = 2, 3, and 4 methylene groups.；For this reason, many experimental approaches have been developed for preparing, sustaining, and detecting long-lived singlet order,32–37 including spin-lock-induced crossing (SLIC),38,39 adiabatic-passage spin order conver- sion (APSOC),40–43 magnetization-to-singlet conversion (M2S),9,44 and other NMR pulse sequences.45–48 Long-lived spin order is not restricted to isolated spin pairs.49,50 It can also arise in symmetric multi-spin systems, where spin states belonging to different irre- ducible representations of the molecular symmetry group may be weakly connected by the dominant relaxation mechanisms.2,51–54 Another important class of
核心结论
Here we show that these relaxation-protected modes follow directly from Redfield relaxation theory.；Specifically, we construct the long-lived subspace, i.e., the zero-eigenvalue subspace of the relaxation superoperator associated with the dominant intra-pair dipole–dipole relaxation mechanism.；It has been shown that chains containing several methylene groups, (−CH2−)N , can support delocalized long-lived modes involving nuclear spins throughout the entire aliphatic chain.17,55–61 In aliphatic chains, each methylene group contains a pair of geminal protons, making the intra- pair dipole–dipole interaction within each −CH2− group the dominant relaxation channel, while weaker inter-pair dipole–dipole interactions provide slower relaxation path- arXiv:2608.07219v1 [quant-ph] 7 Aug 2026 2 ways between different groups. ‖ 结论：A detailed analysis of SLIC excitation pathways in chains of different length, together with the connection between these long-lived operators and spin-wave dynamics, will be presented in forthcoming work.
局限
全文未设独立 limitations 节；结构上为非 RCT 设计，因果推断强度受限。
对本项目的价值
★☆☆☆☆ 相关范围内，作为背景与横向对照收录。
全文来源
出版商 OA PDF（正文 86,184 字符，已过 DOI 逐字 / 标题指纹归属校验）
原文题录
- 英文标题：Origin of long-lived nuclear spin states and coherences in aliphatic chains revealed by relaxation theory.
- 期刊与标识：J Chem Phys · PMID 42956349 · DOI 10.1063/5.0355673
A 级证据分级：A 级（同行评议人体研究）
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