Optimal excitation of N23a nuclear spins in the presence of residual quadrupolar coupling and quadrupolar relaxation

2009 ◽  
Vol 131 (17) ◽  
pp. 174501 ◽  
Author(s):  
Jae-Seung Lee ◽  
Ravinder R. Regatte ◽  
Alexej Jerschow
Keyword(s):  
Nuclear Spins ◽  
Quadrupolar Coupling ◽  
Optimal Excitation ◽  
Quadrupolar Relaxation

A nuclear magnetic resonance relaxation study of liquid hydrogen cyanide

1987 ◽  
Vol 65 (9) ◽  
pp. 2077-2081 ◽  
Author(s):  
Roderick E. Wasylishen
Keyword(s):  
Temperature Dependence ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Correlation Times ◽  
Spin Lattice ◽  
Quadrupolar Coupling ◽  
Quadrupolar Relaxation ◽  
Resonance Relaxation

The rates of 2H, 13C, and 14N spin-lattice relaxation for liquid deuterium cyanide have been studied as a function of temperature. The quadrupolar nuclei relax exclusively by the quadrupolar relaxation mechanism while the rate of 13C and 15N relaxation is completely dominated by the spin-rotation mechanism. The apparent activation energy that describes the temperature dependence of spin-lattice relaxation for all nuclei studied is approximately 1.6 kcal mol−1. The temperature dependence of the rate of 13C relaxation in liquid HCN was also investigated. Although the determination of very accurate rotational and angular momentum correlation times is hampered by intermolecular effects on the nuclear quadrupolar coupling constants and the appropriately averaged C—H bond separation, the derived correlation times for DCN and HCN are in reasonable agreement (± 15%).

Relaxation and phonon bottleneck of 169Tm nuclear spins in TmPO 4 : evidence for the direct process ?

1985 ◽  
Vol 46 (10) ◽  
pp. 1699-1708 ◽  
Author(s):  
Y. Roinel ◽  
V. Bouffard ◽  
J.-F. Jacquinot ◽  
C. Fermon ◽  
G. Fournier
Keyword(s):  
Nuclear Spins ◽  
Direct Process ◽  
Phonon Bottleneck

Strong Coupling of Electron and Nuclear Spins: Outlook and Prospects

2018 ◽  
Author(s):  
M. M. Glazov
Keyword(s):  
Energy Spectrum ◽  
Charge Carrier ◽  
Strong Coupling ◽  
Nuclear Spin ◽  
Spin Dynamics ◽  
Spin Polaron ◽  
Nuclear Spins ◽  
Deep Impurity ◽  
Impurity Centers ◽  
Ordered State

In this chapter, some prospects in the field of electron and nuclear spin dynamics are outlined. Particular emphasis is put ona situation where the hyperfine interaction is so strong that it leads to a qualitative rearrangement of the energy spectrum resulting in the coherent excitation transfer between the electron and nucleus. The strong coupling between the spin of the charge carrier and of the nucleus is realized, for example in the case of deep impurity centers in semiconductors or in isotopically purified systems. We also discuss the effect of the nuclear spin polaron, that is ordered state, formation at low enough temperatures of nuclear spins, where the orientation of the carrier spin results in alignment of the spins of nucleus interacting with the electron or hole.

Electron Spin Decoherence by Nuclei

2018 ◽  
Author(s):  
M. M. Glazov
Keyword(s):  
Electron Spin ◽  
Spin Dynamics ◽  
Magnetic Moments ◽  
Host Lattice ◽  
Spin Model ◽  
Relaxation Processes ◽  
Nuclear Spins ◽  
Model Calculations ◽  
Spin Decoherence ◽  
Quantum Mechanical Approach

The discussion of the electron spin decoherence and relaxation phenomena via the hyperfine interaction with host lattice spins is presented here. The spin relaxation processes processes limit the conservation time of spin states as well as the response time of the spin system to external perturbations. The central spin model, where the spin of charge carrier interacts with the bath of nuclear spins, is formulated. We also present different methods to calculate the spin dynamics within this model. Simple but physically transparent semiclassical treatment where the nuclear spins are considered as largely static classical magnetic moments is followed by more advanced quantum mechanical approach where the feedback of electron spin dynamics on the nuclei is taken into account. The chapter concludes with an overview of experimental data and its comparison with model calculations.

Optimal Excitation of Magnetic Fields

1999 ◽  
Vol 522 (2) ◽  
pp. 1079-1087 ◽  
Author(s):  
Brian F. Farrell ◽  
Petros J. Ioannou
Keyword(s):  
Magnetic Fields ◽  
Optimal Excitation

scholarly journals Relativistic Effects on NMR Parameters of Halogen-Bonded Complexes

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4399 ◽  
Author(s):  
Ibon Alkorta ◽  
José Elguero ◽  
Manuel Yáñez ◽  
Otilia Mó ◽  
M. Merced Montero-Campillo
Keyword(s):  
Relativistic Effects ◽  
Lewis Base ◽  
Coupling Constants ◽  
Basic Site ◽  
Lewis Bases ◽  
Nmr Parameters ◽  
Quadrupolar Coupling ◽  
Binary Complexes ◽  
Computational Level ◽  
Bonded Complexes

Relativistic effects are found to be important for the estimation of NMR parameters in halogen-bonded complexes, mainly when they involve the heavier elements, iodine and astatine. A detailed study of 60 binary complexes formed between dihalogen molecules (XY with X, Y = F, Cl, Br, I and At) and four Lewis bases (NH3, H2O, PH3 and SH2) was carried out at the MP2/aug-cc-pVTZ/aug-cc-pVTZ-PP computational level to show the extent of these effects. The NMR parameters (shielding and nuclear quadrupolar coupling constants) were computed using the relativistic Hamiltonian ZORA and compared to the values obtained with a non-relativistic Hamiltonian. The results show a mixture of the importance of the relativistic corrections as both the size of the halogen atom and the proximity of this atom to the basic site of the Lewis base increase.

scholarly journals A simulation study investigating potential diffusion-based MRI signatures of microstrokes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rafat Damseh ◽  
Yuankang Lu ◽  
Xuecong Lu ◽  
Cong Zhang ◽  
Paul J. Marchand ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Statistical Power ◽  
Barrel Cortex ◽  
Signal Loss ◽  
Nuclear Spins ◽  
Directional Diffusion ◽  
Ischemic Tissue ◽  
Significant Difference ◽  
Before And After ◽  
Experimental Validations

AbstractRecent studies suggested that cerebrovascular micro-occlusions, i.e. microstokes, could lead to ischemic tissue infarctions and cognitive deficits. Due to their small size, identifying measurable biomarkers of these microvascular lesions remains a major challenge. This work aims to simulate potential MRI signatures combining arterial spin labeling (ASL) and multi-directional diffusion-weighted imaging (DWI). Driving our hypothesis are recent observations demonstrating a radial reorientation of microvasculature around the micro-infarction locus during recovery in mice. Synthetic capillary beds, randomly- and radially-oriented, and optical coherence tomography (OCT) angiograms, acquired in the barrel cortex of mice (n = 5) before and after inducing targeted photothrombosis, were analyzed. Computational vascular graphs combined with a 3D Monte-Carlo simulator were used to characterize the magnetic resonance (MR) response, encompassing the effects of magnetic field perturbations caused by deoxyhemoglobin, and the advection and diffusion of the nuclear spins. We quantified the minimal intravoxel signal loss ratio when applying multiple gradient directions, at varying sequence parameters with and without ASL. With ASL, our results demonstrate a significant difference (p < 0.05) between the signal-ratios computed at baseline and 3 weeks after photothrombosis. The statistical power further increased (p < 0.005) using angiograms measured at week 4. Without ASL, no reliable signal change was found. We found that higher ratios, and accordingly improved significance, were achieved at lower magnetic field strengths (e.g., B0 = 3T) and shorter echo time TE (< 16 ms). Our simulations suggest that microstrokes might be characterized through ASL-DWI sequence, providing necessary insights for posterior experimental validations, and ultimately, future translational trials.

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