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For a fully oriented molecule, the dipolar coupling for an 1 H-15 N amide group would be over 20 kHz, and a pair of protons separated by 5 Å would have up to ~1 kHz coupling. However the degree of alignment achieved by applying magnetic field is so low that the largest 1 H-15 N or 1 H-13 C dipolar couplings are <5 Hz. [19]
However, long-range orientation information can be obtained through residual dipolar coupling experiments in a medium which imposes a weak alignment on the nucleic acid molecules. [1] [2] Recently, solid-state NMR methodology has been introduced for the structure determination of nucleic acids. [6]
Solid-state 900 MHz (21.1 T [1]) NMR spectrometer at the Canadian National Ultrahigh-field NMR Facility for Solids. Solid-state nuclear magnetic resonance (ssNMR) is a spectroscopy technique used to characterize atomic-level structure and dynamics in solid materials. ssNMR spectra are broader due to nuclear spin interactions which can be categorized as dipolar coupling, chemical shielding ...
Magnetic dipole–dipole interaction, also called dipolar coupling, refers to the direct interaction between two magnetic dipoles. Roughly speaking, the magnetic field of a dipole goes as the inverse cube of the distance, and the force of its magnetic field on another dipole goes as the first derivative of the magnetic field. It follows that ...
Example 1 H NMR spectrum (1-dimensional) of ethanol plotted as signal intensity vs. chemical shift.There are three different types of H atoms in ethanol regarding NMR. The hydrogen (H) on the −OH group is not coupling with the other H atoms and appears as a singlet, but the CH 3 − and the −CH 2 − hydrogens are coupling with each other, resulting in a triplet and quartet respectively.
The nuclear dipolar interaction has a dependence, where is the angle between the internuclear axis and the main magnetic field. As a result, the dipolar interaction vanish at the magic angle θ m and the interaction contributing to the line broadening is removed. Even though all internuclear vectors cannot be all set to the magic angle ...
The interaction was first derived by Enrico Fermi in 1930. [7] A classical derivation of this term is contained in "Classical Electrodynamics" by J. D. Jackson. [8] In short, the classical energy may be written in terms of the energy of one magnetic dipole moment in the magnetic field B(r) of another dipole.
The "feet" of the lineshape correspond to the situation when the principal axis of the coupling interaction is parallel to the magnetic field which is much less statistically relevant. Pake was the first to describe this lineshape and used it to extract the proton-proton distance from his experiments on a single crystal and powdered hydrates of ...