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In solid-state NMR spectroscopy, magic-angle spinning (MAS) is a technique routinely used to produce better resolution NMR spectra. MAS NMR consists in spinning the sample (usually at a frequency of 1 to 130 kHz ) at the magic angle θ m (ca. 54.74°, where cos 2 θ m =1/3) with respect to the direction of the magnetic field .
Nuclear magnetic resonance (NMR) spectroscopy uses the intrinsic magnetic moment that arises from the spin angular momentum of a spin-active nucleus. [1] If the element of interest has a nuclear spin that is not 0, [1] the nucleus may exist in different spin angular momentum states, where the energy of these states can be affected by an external magnetic field.
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 ...
A better alternative to the use of potentially hazardous oxidizers is an NMR tube cleaner (right). It is an apparatus which uses a vacuum to flush solvent and/or a detergent solution through the entire length of the NMR tube. In this apparatus, the NMR tube 1 (with the cap 3 fixed to the base of the NMR tube), is placed upside down on the ...
The magic angle is a precisely defined angle, the value of which is approximately 54.7356°. The magic angle is a root of a second-order Legendre polynomial, P 2 (cos θ) = 0, and so any interaction which depends on this second-order Legendre polynomial vanishes at the magic angle.
The spin interaction that is usually employed for structural analyses via solid state NMR spectroscopy is the magnetic dipolar interaction. [8] Additional knowledge about other interactions within the studied system like the chemical shift or the electric quadrupole interaction can be helpful as well, and in some cases solely the chemical shift has been employed as e.g. for zeolites. [9]
The spectrum that appears along both the horizontal and vertical axes is a regular one dimensional 1 H NMR spectrum. The bulk of the peaks appear along the diagonal, while cross-peaks appear symmetrically above and below the diagonal. COSY-90 is the most common COSY experiment. In COSY-90, the p1 pulse tilts the nuclear spin by 90°.
Throughout this section, the reduced Planck constant = for convenience.. The product operator formalism is usually applied to sets of spin-1/2 particles, since the fact that the individual operators satisfy = =, where is the identity operator, makes the commutation relations of product operators particularly simple.