A study of the thermal contact between the nuclear Zeeman system and the electron dipole-dipole interaction system

Houten, Judith Van; Wenckebach, W.Th.; Poulis, N.J.

doi:10.1016/0378-4363(77)90021-3

Cited by 23 publications

(42 citation statements)

References 10 publications

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“…where ᏸ is the Zeeman interaction of the paramagnetic impurity spins, ᏸ Ᏽ is the Zeeman interaction of the nuclear spins, Ᏼ is the mutual dipolar interaction of the electron spins, and Ᏼ Ᏽ is the dipolar interaction of the electron spins with the nuclear spins (23). Three different types of thermal reservoirs can be identified, namely, the nuclear Zeeman reservoir (ᏸ Ᏽ ), the electron dipole-dipole interaction reservoir (Ᏼ ), and the electron Zeeman reservoirs (ᏸ ).…”

Section: Thermodynamic Model Of Electron and Nuclear Spin Systemsmentioning

confidence: 99%

“…This mechanism, by which the nuclear Zeeman and dipole-dipole interaction reservoirs interact, requires simultaneous transitions of two electrons and a nuclear spin (5,23). The two electrons, belonging to the same EPR line, perform a flip-flop, yielding an energy quantum n , which in turn induces a nuclear transition, i.e., nuclear spin-lattice relaxation, as illustrated in Fig.…”

Section: Nuclear Spin-lattice Relaxation Mechanismsmentioning

confidence: 99%

“…The homogeneous three-spin mechanism is a correlation time type process (23). It is assumed that crossrelaxation within the electron system is sufficiently fast to establish thermal equilibrium within this system and that the electron spin-spin relaxation time approximates the correlation time associated with this mechanism [T 2 (e) Ϸ T 2 SS (e)], where (5)…”

Section: Nuclear Spin-lattice Relaxation Mechanismsmentioning

confidence: 99%

“…(5) or via electron cross-relaxation processes (23). Usually T 1D is field-independent and of the order of a microsecond (5,26).…”

Section: Figurementioning

confidence: 99%

“…T L is the lattice temperature. Further, ⌬ 2 jm ϭ e j Ϫ e m ϭ ⌬ 2 is the resonance frequency difference between the two electrons, while g() is a line shape function with line width ␦(e), giving the distribution of electron spins in a diluted paramagnetic system, and gЈ(⌬ 2 ) is the convolution of two individual EPR line shapes g( e ) (23). If the individual EPR lines g( e ) and g( e Ϫ ⌬ 2 ) are represented by Gaussian line shapes, both with a width ⑀, the convolution gЈ(⌬ 2 ) is also a Gaussian.…”

Section: Figurementioning

confidence: 99%

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Spin lattice relaxation of spin‐½ nuclei in solids containing diluted paramagnetic impurity centers. I. Zeeman polarization of nuclear spin system

Reynhardt

2003

Concepts Magnetic Resonance

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Spin-lattice relaxation mechanisms of nuclear spins in solids in the presence of low concentrations of paramagnetic centers are discussed. Apart from the electron spin-lattice relaxation mechanism, three-spin processes involving two electron spins and a nuclear spin may also play a role in the spin-lattice relaxation of the nuclear spins. Nuclear spins that are close to a paramagnetic impurity center experience large local fields and do not contribute to the NMR signal. Only a small percentage of nuclear spins surrounding an impurity center are polarized directly. The majority of the nuclear spins are polarized by spin diffusion, which is a slow process. A brief overview of a number of paramagnetic impurity centers, which are common in natural diamond, is given and experimental 13 C spin-lattice relaxation times for a suite of natural diamonds are compared with calculated values.

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Section: Thermodynamic Model Of Electron and Nuclear Spin Systemsmentioning

confidence: 99%

Section: Nuclear Spin-lattice Relaxation Mechanismsmentioning

confidence: 99%

Section: Nuclear Spin-lattice Relaxation Mechanismsmentioning

confidence: 99%

“…(5) or via electron cross-relaxation processes (23). Usually T 1D is field-independent and of the order of a microsecond (5,26).…”

Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

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Spin lattice relaxation of spin‐½ nuclei in solids containing diluted paramagnetic impurity centers. I. Zeeman polarization of nuclear spin system

Reynhardt

2003

Concepts Magnetic Resonance

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On Mechanisms of Dynamic Nuclear Polarization in Solids

Thurber

Tycko

2014

Israel Journal of Chemistry

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Dynamic nuclear polarization (DNP) can dramatically increase the signal in nuclear magnetic resonance (NMR) experiments by transferring spin polarization from electrons to nuclei. We discuss quantum mechanical descriptions of the "solid effect" and "cross effect" mechanisms of DNP that typically occur in solid state NMR at high magnetic field, both with and without magic angle spinning (MAS). We present several extensions of recent theoretical descriptions, including (i) treatments of solid effect DNP and cross effect DNP with MAS, in which two nuclei change spin states simultaneously and (ii) a treatment of solid effect DNP in a two-spin system without MAS, in which the ratio of microwave field strength to hyperfine coupling strength can be arbitrary. We also briefly discuss factors that influence DNP efficiency in experiments, beyond the basic principles contained in simple quantum mechanical models.Keywords: adiabatic rapid passage · cross effect · dynamic nuclear polarization · Landau-Zener · magic angle spinning · NMR spectroscopy · radicals · solid effect Isr.

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13C Spin–Lattice Relaxation in Natural Diamond: Zeeman Relaxation in Fields of 500 to 5000 G at 300 K Due to Fixed Paramagnetic Nitrogen Defects

Terblanche

Reynhardt

Rakitianski

et al. 2001

Solid State Nuclear Magnetic Resonance

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A study of the thermal contact between the nuclear Zeeman system and the electron dipole-dipole interaction system

Cited by 23 publications

References 10 publications

Spin lattice relaxation of spin‐½ nuclei in solids containing diluted paramagnetic impurity centers. I. Zeeman polarization of nuclear spin system

Spin lattice relaxation of spin‐½ nuclei in solids containing diluted paramagnetic impurity centers. I. Zeeman polarization of nuclear spin system

On Mechanisms of Dynamic Nuclear Polarization in Solids

13C Spin–Lattice Relaxation in Natural Diamond: Zeeman Relaxation in Fields of 500 to 5000 G at 300 K Due to Fixed Paramagnetic Nitrogen Defects

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