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nuclear spins

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Published: 15 December 2019
Fig. 1 Schematic showing the nuclear spin energy levels as a function of spin quantum number, I , and externally applied magnetic field, B 0 . The central transition (+1/2 to −1/2, in red) is denoted, and satellite transitions (in blue) also are shown. The Larmor frequency (splitting), ω L More
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006650
EISBN: 978-1-62708-213-6
... Abstract This article focuses on the application of solid-state nuclear magnetic resonance (NMR) spectroscopy in materials science, especially for inorganic and organic polymer solids. It begins with a discussion on the general principles of NMR, providing information on nuclear spin...
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Published: 01 January 1986
Fig. 9 Hyperfine structure patterns. Three equally coupled nuclei with nuclear spin I = 1 2 and coupling constant A p plus two equally coupled I = 1 nuclei with coupling constant. (a) A N ≪ A p . (b) A N ≫ A p . (c) A N = A p More
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001752
EISBN: 978-1-62708-178-8
... dipole and electric quadrupole undoubtedly exist, their interaction energies are orders of magnitude smaller and can be neglected. Values for the nuclear spin I , gyromagnetic ratio γ, and quadrupole moment Q for various nuclei are given in Table 1 . Also given are the naturally occurring relative...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001750
EISBN: 978-1-62708-178-8
... carried out using ESR spectrometers irradiate the unpaired spins with a microwave frequency (approximately 10 10 Hz) and a RF (approximately 10 7 Hz). Many of these are nuclear-polarization techniques; therefore, the nuclear spin levels become populated with a Boltzmann factor characteristic of electron...
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Published: 15 December 2019
Fig. 3 Photo of a standard magic-angle spinning (MAS) nuclear magnetic resonance (NMR) probe (Chemagnetics/Varian wide-bore design, 89 mm, or 3.5 in.). The sample rotor is inserted into the MAS housing through the opening near the top of the probe. Air attachments, for both drive and bearing More
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Published: 15 December 2019
Fig. 4 Examples of two widely available standard magic-angle spinning nuclear magnetic resonance rotor (sample holder) sizes. The cylindrical sleeve typically is zirconia, although silicon nitride also is used in some applications. The endcap, spacer, and drive tip shown for the 3.2 mm (0.13 More
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Published: 15 December 2019
Fig. 5 A 9.5 mm (0.37 in.) magic-angle spinning nuclear magnetic resonance (MAS NMR) rotor (drive tip not fully inserted for clarity) along with a typical glass insert that can contain nonsolid samples and fit tightly into the zirconia rotor for standard MAS NMR experiments. A synthetic More
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Published: 15 December 2019
Fig. 8 The 31 P magic-angle spinning nuclear magnetic resonance spectra of crystalline Sn 2 P 2 O 7 with (a) no apodization and (b) 200 Hz Gaussian line broadening. Only the isotropic peaks due to the two Q 1 polyhedra are shown. More
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Published: 15 December 2019
Fig. 9 The 31 P magic-angle spinning nuclear magnetic resonance spectra of glassy 10Na 2 O·45CaO·45P 2 O 5 . (a) Spectrum showing only the isotropic peaks. (b) Full spectrum with all spinning sidebands (ssb). Gaussian fits to the isotropic peaks and associated spinning sidebands are shown More
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Published: 15 December 2019
Fig. 10 Examples of (a) 11 B magic-angle spinning nuclear magnetic resonance (MAS NMR) spectrum (16.4 T) of a sodium borosilicate glass with composition of 33Na 2 O-53B 2 O 3 -14SiO 2 and (b) 27 Al MAS NMR spectrum (16.4 T) of a glass with composition of 20CaO-30Al 2 O 3 -50SiO 2 More
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Published: 15 December 2019
Fig. 11 The 29 Si magic-angle spinning nuclear magnetic resonance spectrum of a cordierite (aluminosilicate) ceramic. This ceramic contains two different tetrahedral sites, denoted T 1 and T 2 , each of which is occupied by silicate tetrahedra having different numbers of next-nearest More
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Published: 15 December 2019
Fig. 13 Solid-state magic-angle spinning nuclear magnetic resonance (NMR) spectra of (a) 29 Si and (b) 27 Al in a β-spodumene glass-ceramic, before and after heat treatment. Spinning sidebands are marked as “ssb,” and dashed curves denote fitted peaks. More
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Published: 15 December 2019
Fig. 14 The 13 C cross-polarization magic-angle spinning nuclear magnetic resonance spectrum of modified cellulose powder. Different peaks are labeled with their position in the cellulose backbone: the hydroxypropyl (HP) and methoxy (Me) modifications. More
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Published: 15 December 2019
Fig. 15 The 13 C cross-polarization magic-angle spinning nuclear magnetic resonance spectrum of silica gel treated with γ-aminopropyl triethoxysilane. Two resonances from unreacted ethoxide functionality are identified, and the other three resonances are from the aminopropyl group More
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Published: 01 January 1986
the time period t w ( a to b ). The RF field is turned off suddenly at b. The spins begin to spread out as the result of an assumed magnetic-field inhomogeneity. Some spins precess faster than the rotating frame; others precess slower. A decaying nuclear signal is seen during bb ′. The spins have More
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Published: 15 December 2019
Fig. 6 The 31 P nuclear magnetic resonance (NMR) spectra of crystalline Sn 2 P 2 O 7 at 11.7 T (ω L = 202 MHz) using a 3.2 mm (0.13 in.) magic-angle spinning (MAS) NMR probe. The spectrum in (a) was obtained under static conditions (i.e., no sample spinning), while the other spectra were More
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Published: 15 December 2019
Fig. 12 Additional examples of solid-state nuclear magnetic resonance studies of ceramics. (a) 27 Al magic-angle spinning nuclear magnetic resonance (MAS NMR) spectrum of γ-alumina, showing resolution of aluminum in tetrahedral and octahedral sites. (b) 1 H MAS NMR spectrum of H-ZSM-5 More
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006646
EISBN: 978-1-62708-213-6
... 1 1 + α where I e is the spin of the excited nuclear state, I g is the spin of the ground state, and α is the internal conversion coefficient. When the excited- and ground-state energy levels are split by a hyperfine field, the cross section is divided proportionally among the various...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001753
EISBN: 978-1-62708-178-8
... 59.537 (radioactive) 68.3 5 2 5 2 32.55 0.06727 93.2 75 Note: E γ , is the γ-ray energy of the Mössbauer transition, t 1/2 is the half-life of the excited Mössbauer level, I e and I g are the spins of the excited- and ground-state nuclear levels, σ 0...