Long-lived nuclear spin states (LLS) are configurations of nuclear spins which are protected against common relaxation or dissipation mechanisms and which display extended decay time constants . A seminal example is the singlet order of a spin-1/2 pair ensemble, corresponding to a population imbalance between the singlet and triplet states of the spin-1/2 pairs . The decay time constants of such states are often many times the spinlattice relaxation time constant T 1 , with lifetimes exceeding 1 hour being observed in favourable cases . Longlived states have been applied to the study of slow chemical and transport processes , to the characterisation of biomolecular ligand binding , and for the transport and storage of nuclear hyperpolarization . Longlived nuclear singlet order plays a central role in the generation of nuclear hyperpolarization from hydrogen gas enriched in the para spin isomer .