Singlet lifetime measurements in an all-proton chemically equivalent spin system by hyperpolarization and weak spin lock transfers

Abstract

Hyperpolarized singlet states provide the opportunity for polarization storage over periods significantly longer than T1. Here, we show how the singlet state in a chemically equivalent proton spin system can be revealed by a weak power spin-lock. This procedure allowed the measurement of the lifetimes of the singlet state in protic solvents. The contributions of different intra- and intermolecular relaxation mechanisms to singlet lifetimes are investigated with this procedure.

Long-lived nuclear spin states in monodeuterated methyl groups

“…However, the range of hyperpolarization applications is restricted by the finite lifetime of the enhanced magnetization, which is normally limited by T 1 . The use of LLS offers a promising means to transcend this limitation [9,[25][26][27][28].…”

Long-lived nuclear spin states in rapidly rotating CH 2 D groups

“…The population imbalance between the singlet state and the triplet states is called singlet order and is protected against many common relaxation mechanisms [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The relaxation time constant for singlet order is called T S and often exceeds the conventional longitudinal relaxation time T 1 by a large factor [16][17][18][19][20][21][22]. Applications of singlet order to hyperpolarized NMR experiments have been proposed [8,[23][24][25][26][27][28].…”

“…The relaxation time constant for singlet order is called T S and often exceeds the conventional longitudinal relaxation time T 1 by a large factor [16][17][18][19][20][21][22]. Applications of singlet order to hyperpolarized NMR experiments have been proposed [8,[23][24][25][26][27][28].…”

Prediction of low-field nuclear singlet lifetimes with molecular dynamics and quantum-chemical property surface

“…These regions are determined by testing several candidate regions, separately for each of the spins j and k, in a screening process. We are interested in the maximum contribution of T S [SIM], i.e., the integral of TCF, eqn (22). For practical purposes, it is convenient not to include the tensors (needed in eqn (22)) at this stage.…”

“…In strong magnetic fields, chemical shift anisotropy (CSA) often dominates the relaxation of nuclear singlet order. Fast molecular tumbling, compared to both the CSA interaction and the nuclear Larmor frequency, gives rise to a quadratic dependence of T −1 S on the magnetic field strength 19,21,22 . One unusual feature of the CSA mechanism of singlet relaxation is that the antisymmetric (rank-1) components of the CSA tensor often dominate 19 .…”