Long-lived states (LLS) involving pairs of magnetically inequivalent but chemically equivalent proton spins in aliphatic (CH2)n chains can be excited by simultaneous application of weak selective radio-frequency (RF) fields at n chemical shifts by polychromatic spin lock induced crossing (poly-SLIC). The LLS are delocalized throughout the aliphatic chain by mixing of intrapair singlet states and by excitation of LLS comprising products of four or six spins. The measured lifetimes TLLS in a model compound are about 5 times longer than T1, and are strongly affected by interactions with macromolecules.
@article{arxiv.2207.03446,
title = {Polychromatic Excitation of Delocalized Long-Lived Proton Spin States in Aliphatic Chains},
author = {Anna Sonnefeld and Geoffrey Bodenhausen and Kirill Sheberstov},
journal= {arXiv preprint arXiv:2207.03446},
year = {2022}
}