Spin-lattice relaxation of coupled nuclear spins with applications to molecular motion in liquids

A Novel Model-Free Analysis of13C NMR Relaxation of Alanine-Methyl Side-Chain Motions in Peptides

“…A simple 13 C NMR relaxation studies of proteins provide many ex-model-free approach to calculate rotational-correlation funcperimental parameters such as spin-lattice and spin-spin tions parameterized with both a standard order parameter relaxation rates, cross-relaxation rates (via { 1 H} - 13 C and a novel ''mixing'' parameter is presented, and the sensi-NOE), two-spin relaxation rates of longitudinal two-spin tivity of methyl-group NMR relaxation parameters to backorder and of anti-phase coherence (1,2), and various cross-bone mobility is addressed. correlation spectral densities for dipole-dipole (3)(4)(5)(6)(7)(8) and dipole-chemical-shift anisotropy interactions (9,10). Exper-e.g., CSA and spin rotation, then neglecting cross-correlation 1/T 1 Å (1/10)k D [J CH (v C 0 v H ) / 3J CH (v C ) terms leads to inflated NOEs.…”

Simple organofluorine compounds giving field‐dependent 13C and 19F NMR spectra with complex patterns: higher order effects and cross‐correlated relaxation

“…[36] We are not aware of any corresponding reports for 13 CF 3 groups, although cross-correlated relaxation has been demonstrated for the 13 C-19 F pair in CHFCl 2 (nonexponential relaxation in a 1 H-decoupled 13 C inversion-recovery experiment). [47] Interference effects can occur between relaxation mechanisms that transform in a similar manner, [31,48] i.e. the tensors that describe the time dependence of the interactions are of the same rank.…”

Cross Correlations in the Longitudinal Relaxation of Strongly Coupled Spins

“…The superscripts (1, 7) and (2,8) refer to the two double quanta of the A and the B spins while (3,4) and (5,6) refer to the zero quanta of these spins (where ͉1͘ ϭ ␣␣␣, ͉2͘ ϭ ␣␣␤, ͉3͘ ϭ cos ϩ ␣␤␣ ϩ sin ϩ ␤␣␣, ͉4͘ ϭ Ϫsin ϩ ␣␤␣ ϩ cos ϩ ␤␣␣, ͉5͘ ϭ cos Ϫ ␣␤␤ ϩ sin Ϫ ␤␣␤, ͉6͘ ϭ Ϫsin Ϫ ␣␤␤ ϩ cos Ϫ ␤␣␤, ͉7͘ ϭ ␤␤␣, and ͉8͘ ϭ ␤␤␤, with the usual definitions of Ϯ (34)). The labels (1, 2), (3,5), (4,6), and (7,8) refer to the single-quantum transitions of the X spin.…”

“…The labels (1, 2), (3,5), (4,6), and (7,8) refer to the single-quantum transitions of the X spin. Here, the single-transition operator basis for the LMQM modes encompasses the double-quantum-zero-quantum subspace of the two strongly coupled spins and the single-quantum subspace of the weakly coupled spin.…”

“…Although the form of the Redfield equation is mathematically elegant, computing individual matrix elements for different spin systems is tedious and often provides little insight into multispin relaxation. A transformation to the basis of "modes," many of which can be directly related to physical observables, proves more useful (3)(4)(5)(6). For longitudinal relaxation, these modes (known as "magnetization modes") are essentially various linear combinations of the populations of different energy levels, and have been used with great success to gain tangible structural and dynamic information in weakly coupled spin systems (7,8).…”