View source for Solid-state nuclear magnetic resonance

[[Image:900 magnet new.jpg|thumb|right|300px|Solid-state 900 MHz (21.1 T<ref>{{cite web |url=http://nmr900.ca/instrument_e.html |title=National Ultrahigh-Field NMR Facility for Solids |accessdate=2014-09-22 }}</ref>) 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, [[Quadrupole|quadrupolar interactions]], and [[j-coupling]]. These interactions directly affect the lines shapes of experimental ssNMR spectra which can be seen in powder and dipolar patterns. There are many essential solid-state techniques alongside advanced ssNMR techniques that may be applied to elucidate the fundamental aspects of solid materials. ssNMR is often combined with [[magic angle spinning]] (MAS) to remove [[Anisotropy|anisotropic]] interactions and improve the sensitivity of the technique. The applications of ssNMR further extend to [[biology]] and [[medicine]]. 
[[File:MAS rotors.jpg|thumb|Bruker MAS rotors. From left to right: 1.3 mm (up to 67 kHz), 2.5 mm (up to 35 kHz), 3.2 mm (up to 24 kHz), 4 mm (up to 15 kHz), 7 mm (up to 7 kHz)]]

== Nuclear spin interactions ==
<!-- Magnitude of interaction... -->The [[resonance frequency]] of a [[nuclear spin]] depends on the strength of the [[magnetic field]] at the [[Atomic nucleus|nucleus]], which can be modified by isotropic (e.g. [[chemical shift]], isotropic J-[[J-coupling|coupling]]) and anisotropic interactions ([[Chemical shift anisotropy|e.g. chemical shift anisotropy]], dipolar interactions). In a classical liquid-state NMR experiment, molecular tumbling coming from [[Brownian motion]] averages anisotropic interactions to zero and they are therefore not reflected in the NMR spectrum. However, in media with no or little mobility (e.g. crystalline powders, glasses, large membrane vesicles, molecular aggregates), anisotropic local fields or interactions have substantial influence on the behaviour of nuclear spins, which results in the line broadening of the NMR spectra.

=== Chemical shielding ===
{{Main articles|Chemical shift}}
Chemical shielding is a local property of each nuclear site in a molecule or compound, and is proportional to the applied external magnetic field. The external magnetic field induces currents of the electrons in molecular orbitals. These induced currents create local magnetic fields that lead to characteristic changes in resonance frequency. These changes can be predicted from molecular structure using empirical rules or quantum-chemical calculations.

In general, the chemical shielding is anisotropic because of the anisotropic distribution of molecular orbitals around the nuclear sites. Under sufficiently fast magic angle spinning, or under the effect of molecular tumbling in solution-state NMR, the anisotropic dependence of the chemical shielding is time-averaged to zero, leaving only the isotropic [[chemical shift]].

=== Dipolar coupling ===
{{main|Magnetic dipole-dipole interaction}}
[[Image:SSNMR dip coupl vect.png|thumb|Vectors important for dipolar coupling between nuclear spins I<sub>1</sub> and I<sub>2</sub>. θ is the angle between the vector connecting I<sub>1</sub> and I<sub>2</sub>, and the magnetic field B.]]
Nuclear spins exhibit a [[Nuclear magnetic moment|magnetic dipole moment]], which generates a magnetic field that interacts with the dipole moments of other nuclei ([[dipolar coupling]]). The magnitude of the interaction is dependent on the [[gyromagnetic ratio]] of the spin species, the internuclear distance ''r'', and the orientation, with respect to the external magnetic field ''B'', of the vector connecting the two nuclear spins (see figure). The maximum dipolar coupling is given by the dipolar coupling constant ''d'',
: <math> d = \hbar \left( \frac{\mu_0}{4 \pi} \right) \frac{1}{r^3}\gamma_1 \gamma_2 </math>,
where ''γ''<sub>1</sub> and ''γ''<sub>2</sub> are the [[gyromagnetic ratio]]s of the nuclei, <math>\hbar</math> is the [[reduced Planck constant]], and <math>\mu_0
</math> is the [[vacuum permeability]]. In a strong magnetic field, the dipolar coupling depends on the angle ''θ'' between the internuclear vector and the external magnetic field ''B'' (figure) according to
: <math>D \propto 3\cos^2\theta - 1</math>.
''D'' becomes zero for <math>\theta_m = \arccos \sqrt{1/3}= \arctan \sqrt{2} \simeq 54.7^\circ</math>. Consequently, two nuclei with a dipolar coupling vector at an angle of ''θ''<sub>m</sub> = 54.7° to a strong external magnetic field have zero dipolar coupling. ''θ''<sub>m</sub> is called the [[magic angle]]. Magic angle spinning is typically used to remove dipolar couplings weaker than the spinning rate.

=== Quadrupolar interaction ===
{{main|Quadrupole}}

Nuclei with a spin quantum number >1/2 have a non-spherical charge distribution and a quadrupole moment.<ref name=":6">{{Cite web |date=2013-10-02 |title=Quadrupolar Coupling |url=https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Magnetic_Resonance_Spectroscopies/Nuclear_Magnetic_Resonance/NMR_-_Theory/NMR_Interactions/Quadrupolar_Coupling |access-date=2024-12-01 |website=Chemistry LibreTexts |language=en}}</ref> The quadrupole moment is a [[Tensor product|second rank tensor]] that couples to the surrounding [[electric field gradient]], another second rank tensor.<ref name=":6" /><ref>{{Cite book |last=Pfeifer |first=Harry |title=Special Applications |last2=Barker |first2=Philip |date=1993 |publisher=Springer |isbn=978-3-642-50048-0 |series=NMR Basic Principles and Progress |location=Berlin Heidelberg}}</ref> Nuclear quadrupole coupling is typically the second largest interaction in NMR, comparable in size to the largest interaction called [[Zeeman effect|Zeeman interactions]].<ref>{{Cite web |date=2013-10-02 |title=NMR Interactions |url=https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Magnetic_Resonance_Spectroscopies/Nuclear_Magnetic_Resonance/NMR_-_Theory/NMR_Interactions#:~:text=The%20Zeeman%20interaction%20is%20the,is%20only%20tens%20of%20Hz. |access-date=2024-12-02 |website=Chemistry LibreTexts |language=en}}</ref> When the nuclear quadrupole coupling is not negligible relative to the Zeeman coupling, higher order corrections are needed to describe the NMR spectrum correctly. In such cases, the first-order correction to the NMR transition frequency leads to a strong anisotropic line broadening of the NMR spectrum. However, all symmetric transitions, between <math>m_I</math> and <math>-m_I</math> levels are unaffected by the first-order frequency contribution. The second-order frequency contribution depends on the P<sub>4</sub> [[Legendre polynomials|Legendre polynomial]], which has zero points at 30.6° and 70.1°. These anisotropic broadenings can be removed using DOR (DOuble angle Rotation) where you spin at two angles at the same time, or [[A|DAS (Double Angle Spinning)]]<ref>{{Cite journal|date=2007-09-01|title=Design and construction of a contactless mobile RF coil for double resonance variable angle spinning NMR|url=https://www.sciencedirect.com/science/article/abs/pii/S109078070700198X|journal=Journal of Magnetic Resonance|language=en|volume=188|issue=1|pages=183–189|doi=10.1016/j.jmr.2007.06.006|issn=1090-7807|last1=Qian|first1=Chunqi|last2=Pines|first2=Alex|last3=Martin|first3=Rachel W.|pmid=17638585|bibcode=2007JMagR.188..183Q }}</ref> where you switch quickly between the two angles. Both techniques were developed in the late 1980s, and require specialized hardware (probe). Multiple quantum magic angle spinning (MQMAS) NMR was developed in 1995 and has become a routine method for obtaining high resolution solid-state NMR spectra of quadrupolar nuclei.<ref>{{cite journal |author1=Frydman Lucio |author2=Harwood John S | year = 1995 | title = Isotropic Spectra of Half-Integer Quadrupolar Spins from Bidimensional Magic-Angle Spinning NMR | journal = J. Am. Chem. Soc. | volume = 117 | issue = 19| pages = 5367–5368 | doi=10.1021/ja00124a023}}</ref><ref>{{cite journal |author1=Massiot D. |author2=Touzo B. |author3=Trumeau D. |author4=Coutures J. P. |author5=Virlet J. |author6=Florian P. |author7=Grandinetti P. J. | year = 1996 | title = Two-dimensional Magic-Angle Spinning Isotropic Reconstruction Sequences for Quadrupolar Nuclei | journal = Solid-State NMR | volume = 6 | issue = 1| pages = 73–83 | doi=10.1016/0926-2040(95)01210-9|pmid=8925268 }}</ref> A similar method to MQMAS is satellite transition magic angle spinning (STMAS) NMR developed in 2000.

=== J-coupling ===
The [[J-coupling]] or indirect nuclear spin-spin coupling (sometimes also called "scalar" coupling despite the fact that '''J''' is a tensor quantity) describes the interaction of nuclear spins through [[chemical bonds]]. J-couplings are not always resolved in solids owing to the typically large linewdiths observed in solid state NMR.

=== Other interactions ===
[[Paramagnetism|Paramagnetic]] substances are subject to the [[Knight shift]].

== Solid-state NMR line shapes ==
=== Powder pattern ===
[[File:Powder pattern.svg|thumb|Simulations of the shape of different powder patterns for different asymmetry  <math>\eta</math> and chemical shift anisotropy <math>\Delta_{CS}</math>parameters.]]
A powder pattern arises in powdered samples where crystallites are randomly oriented relative to the magnetic field so that all molecular orientations are present. In presence of a chemical shift anisotropy interaction, each orientation with respect to the magnetic field gives a different resonance frequency. If enough crystallites are present, all the different contributions overlap continuously and lead to a smooth spectrum.

Fitting of the pattern in a static ssNMR experiment gives information about the shielding tensor, which are often described by the isotropic chemical shift <math>\delta_{iso}</math>, the chemical shift anisotropy parameter <math>\Delta_{CS}</math>, and the asymmetry parameter <math>\eta</math>.<ref name="auto">{{Cite book|last=Duer|first=Melinda J.|url=https://www.worldcat.org/oclc/53178681|title=Introduction to solid-state NMR spectroscopy|date=2004|publisher=Blackwell|isbn=1-4051-0914-9|location=Oxford, UK|oclc=53178681}}</ref>

=== Dipolar pattern ===
{{See|Pake doublet}}
[[File:Simulation of a dipolar coupling powder pattern in a heteronuclear two spin system.svg|thumb|Dipolar powder pattern (Pake pattern)|left]]

The dipolar powder pattern (also Pake pattern) has a very characteristic shape that arises when two nuclear spins are coupled together within a crystallite. The splitting between the maxima (the "horns") of the pattern is equal to the dipolar coupling constant <math>d</math>.:{{r|auto}}
: <math>d = \hbar \left( \frac{\mu_0}{4 \pi} \right) \frac{1}{r^3}\gamma_1 \gamma_2</math>
where ''γ''<sub>1</sub> and ''γ''<sub>2</sub> are the [[gyromagnetic ratio]]s of the dipolar-coupled nuclei, <math>r</math> is the internuclear distance, <math>\hbar</math> is the [[reduced Planck constant]], and <math>\mu_0
</math> is the [[vacuum permeability]].

== Essential solid-state techniques ==
=== Magic angle spinning ===
{{Main articles|Magic angle spinning}}
[[File:Glycine 13C 9.4T MAS 20khz.gif|thumb|Simulation of an increasing MAS rate on the <sup>13</sup>C solid-state NMR spectrum of <sup>13</sup>C-Glycine at 9.4 T (400 MHz <sup>1</sup>H frequency). MAS introduces a set of spinning sidebands separated from the isotropic frequency by a multiple of the spinning rate.]]
Magic angle spinning (MAS) is a technique routinely used in ssNMR to improve ssNMR spectra resolution.<ref name=":4">{{Cite book |last=Mehring |first=Michael |title=Principles of high resolution NMR in solids |date=1983 |publisher=Springer |isbn=978-3-642-68758-7 |edition=Second, revised and enlarged edition, softcover reprint of the hardcover 2nd edition 1983 |location=Berlin Heidelberg New York}}</ref> After applying the MAS technique, NMR spectra will be sharper and narrower.<ref name=":4" /><ref name=":5">{{Cite book |last=Apperley |first=David C. |title=Solid-state NMR: basic principles & practice |last2=Harris |first2=Robin K. |last3=Hodgkinson |first3=Paul |date=2012 |publisher=Momentum Press, LLC |isbn=978-1-60650-350-8 |location=New York}}</ref> This improved resolution results from manipulating a sample's spin interactions with the applied [[magnetic field]]. This is achieved by rotating the sample at a certain angle to the magnetic field to fully or partially average out [[Anisotropy|anisotropic]] nuclear interactions such as [[Dipolar coupling|dipolar]], [[chemical shift anisotropy]], [[Solid-state nuclear magnetic resonance#Quadrupolar interaction|and quadrupolar]] interactions.<ref name=":4" /> This rotation angle is called the [[magic angle]] θ<sub>m</sub> (ca. 54.74°, where cos<sup>2</sup>''θ''<sub>m</sub> = 1/3). To achieve the complete averaging of these interactions, the sample needs to be spun at a rate that is at least higher than the largest anisotropy.<ref name=":4" /><ref name=":5" />

Spinning a powder sample at a slower rate than the largest component of the chemical shift anisotropy results in an incomplete averaging of the interaction, and produces a set of spinning sidebands in addition to the isotropic line, centred at the isotropic chemical shift.<ref name=":5" /> Spinning sidebands are sharp lines separated from the isotropic frequency by a multiple of the spinning rate. Although spinning sidebands can be used to measure anisotropic interactions, they are often undesirable and removed by spinning the sample faster or by recording the data points synchronously with the rotor period.

=== Cross-polarization ===
[[Image:Cross-polarization.png|thumb|alt=Cross-polarization pulse sequence|200px|right|The CP pulse sequence. The sequence starts with a 90º pulse on the abundant channel (typically H). Then CP contact pulses matching the Hartmann-Hahn condition are applied to transfer the magnetisation from H to X. Finally, the free induction decay (FID) of the X nuclei is detected, typically with <sup>1</sup>H decoupling.]]

[[Cross-polarization]] (CP) if a fundamental (Radiofrequency) RF pulse sequence and a building-block in many solid-state NMR. It is typically used to enhance the signal of a dilute nuclei with a low gyromagnetic ratio (e.g. {{chem|13|C}}, {{chem|15|N}}) by magnetization transfer from an abundant nuclei with a high gyromagnetic ratio (e.g. {{chem|1|H}}), or as a spectral editing method to get through space information (e.g. directed {{chem|15|N}}→{{chem|13|C}} CP in protein spectroscopy).<ref name=":4" />

To establish magnetization transfer, RF pulses ("contact pulses") are simultaneously applied on both frequency channels to produce <math>B_1</math> fields whose strength fulfil the Hartmann–Hahn condition:<ref>{{cite journal|last1=Hartmann |first1=S. R. |last2=Hahn |first2=E. L. |title=Nuclear Double Resonance in the Rotating Frame |journal= Phys. Rev. |volume=128 |year=1962 |issue=5 |pages= 2042–2053 |doi=10.1103/PhysRev.128.2042 |bibcode=1962PhRv..128.2042H |url=http://astrophysics.fic.uni.lodz.pl/100yrs/pdf/09/065.pdf}}</ref><ref>{{Cite journal|last1=Stejskal|first1=E.O|last2=Schaefer|first2=Jacob|last3=Waugh|first3=J.S|date=October 1977|title=Magic-angle spinning and polarization transfer in proton-enhanced NMR|url=https://linkinghub.elsevier.com/retrieve/pii/0022236477902608|journal=Journal of Magnetic Resonance|language=en|volume=28|issue=1|pages=105–112|doi=10.1016/0022-2364(77)90260-8|bibcode=1977JMagR..28..105S }}</ref>
: <math>\gamma_H B_1(^{1}\text{H}) = \gamma_X B_1(\text{X}) \pm n \omega_R</math>
where <math>\gamma</math> are the [[gyromagnetic ratio]]s, <math>\omega_R</math> is the spinning rate, and <math>n</math> is an integer. In practice, the pulse power, as well as the length of the contact pulse are experimentally optimised. The power of one contact pulse is typically ramped to achieve a more broadband and efficient magnetisation transfer.

=== Decoupling ===
Spin interactions can be removed ([[Nuclear magnetic resonance decoupling|decoupled]]) to increase the resolution of NMR spectra during the detection, or to extend the lifetime of the nuclear magnetization.

Heteronuclear decoupling is achieved by radio-frequency irradiation on at the frequency of the nucleus to be decoupled, which is often <sup>1</sup>H. The irradiation can be continuous (continuous wave decoupling<ref>{{Cite journal|last1=Haeberlen|first1=U.|last2=Waugh|first2=J. S.|date=1968-11-10|title=Coherent Averaging Effects in Magnetic Resonance|url=https://link.aps.org/doi/10.1103/PhysRev.175.453|journal=Physical Review|language=en|volume=175|issue=2|pages=453–467|doi=10.1103/PhysRev.175.453|bibcode=1968PhRv..175..453H |issn=0031-899X}}</ref>), or a series of pulses that extend the performance and the bandwidth of the decoupling (TPPM,<ref>{{Cite journal|last1=Bennett|first1=Andrew E.|last2=Rienstra|first2=Chad M.|last3=Auger|first3=Michèle|last4=Lakshmi|first4=K. V.|last5=Griffin|first5=Robert G.|date=1995-10-22|title=Heteronuclear decoupling in rotating solids|url=http://aip.scitation.org/doi/10.1063/1.470372|journal=The Journal of Chemical Physics|language=en|volume=103|issue=16|pages=6951–6958|doi=10.1063/1.470372|bibcode=1995JChPh.103.6951B |issn=0021-9606}}</ref> SPINAL-64,<ref>{{Cite journal|last1=Fung|first1=B.M.|last2=Khitrin|first2=A.K.|last3=Ermolaev|first3=Konstantin|date=2000|title=An Improved Broadband Decoupling Sequence for Liquid Crystals and Solids|url=https://linkinghub.elsevier.com/retrieve/pii/S1090780799918967|journal=Journal of Magnetic Resonance|language=en|volume=142|issue=1|pages=97–101|doi=10.1006/jmre.1999.1896|pmid=10617439|bibcode=2000JMagR.142...97F }}</ref> SWf-TPPM<ref>{{Cite journal|last1=Thakur|first1=Rajendra Singh|last2=Kurur|first2=Narayanan D.|last3=Madhu|first3=P.K.|date=2006|title=Swept-frequency two-pulse phase modulation for heteronuclear dipolar decoupling in solid-state NMR|url=https://linkinghub.elsevier.com/retrieve/pii/S000926140600830X|journal=Chemical Physics Letters|language=en|volume=426|issue=4–6|pages=459–463|doi=10.1016/j.cplett.2006.06.007|bibcode=2006CPL...426..459T }}</ref>)

Homonuclear decoupling is achieved with multiple-pulse sequences (WAHUHA,<ref>{{Cite journal|last1=Waugh|first1=J. S.|last2=Huber|first2=L. M.|last3=Haeberlen|first3=U.|date=1968-01-29|title=Approach to High-Resolution nmr in Solids|url=https://link.aps.org/doi/10.1103/PhysRevLett.20.180|journal=Physical Review Letters|language=en|volume=20|issue=5|pages=180–182|doi=10.1103/PhysRevLett.20.180|bibcode=1968PhRvL..20..180W |issn=0031-9007}}</ref> MREV-8,<ref>{{Cite journal|last1=Rhim|first1=W-K.|last2=Elleman|first2=D. D.|last3=Vaughan|first3=R. W.|date=1973-02-15|title=Enhanced resolution for solid state NMR|url=http://aip.scitation.org/doi/10.1063/1.1679423|journal=The Journal of Chemical Physics|language=en|volume=58|issue=4|pages=1772–1773|doi=10.1063/1.1679423|bibcode=1973JChPh..58.1772R |issn=0021-9606}}</ref> BR-24,<ref name="auto1">{{Cite journal|last1=Burum|first1=D.P|last2=Linder|first2=M|last3=Ernst|first3=R.R|date=July 1981|title=Low-power multipulse line narrowing in solid-state NMR|url=https://linkinghub.elsevier.com/retrieve/pii/0022236481902006|journal=Journal of Magnetic Resonance|language=en|volume=44|issue=1|pages=173–188|doi=10.1016/0022-2364(81)90200-6|bibcode=1981JMagR..44..173B }}</ref> BLEW-12,{{r|auto1}} FSLG<ref>{{Cite journal|last1=Lee|first1=Moses|last2=Goldburg|first2=Walter I.|date=1965-11-15|title=Nuclear-Magnetic-Resonance Line Narrowing by a Rotating rf Field|url=https://link.aps.org/doi/10.1103/PhysRev.140.A1261|journal=Physical Review|volume=140|issue=4A|pages=A1261–A1271|doi=10.1103/PhysRev.140.A1261|bibcode=1965PhRv..140.1261L }}</ref>), or continuous wave modulation (DUMBO,<ref>{{Cite journal |last1=Sakellariou |first1=Dimitris |last2=Lesage |first2=Anne |author-link2=Anne Lesage |last3=Hodgkinson |first3=Paul |last4=Emsley |first4=Lyndon |date=March 2000 |title=Homonuclear dipolar decoupling in solid-state NMR using continuous phase modulation |url=https://linkinghub.elsevier.com/retrieve/pii/S0009261400001275 |journal=Chemical Physics Letters |language=en |volume=319 |issue=3–4 |pages=253–260 |bibcode=2000CPL...319..253S |doi=10.1016/S0009-2614(00)00127-5}}</ref> eDUMBO<ref>{{Cite journal|last1=Paruzzo|first1=Federico M.|last2=Emsley|first2=Lyndon|date=December 2019|title=High-resolution 1H NMR of powdered solids by homonuclear dipolar decoupling|url=https://linkinghub.elsevier.com/retrieve/pii/S109078071930237X|journal=Journal of Magnetic Resonance|language=en|volume=309|pages=106598|doi=10.1016/j.jmr.2019.106598|pmid=31586820|bibcode=2019JMagR.30906598P |s2cid=203139911 |doi-access=free}}</ref>). Dipolar interactions can also be removed with [[magic angle spinning]]. Ultra fast MAS (from 60&nbsp;kHz up to above 111&nbsp;kHz) is an efficient way to average all dipolar interactions, including <sup>1</sup>H–<sup>1</sup>H homonuclear dipolar interactions, which extends the resolution of <sup>1</sup>H spectra and enables the usage of pulse sequences used in solution state NMR.<ref>{{Cite journal|last1=Zhang|first1=Rongchun|last2=Mroue|first2=Kamal H.|last3=Ramamoorthy|first3=Ayyalusamy|date=2017-04-18|title=Proton-Based Ultrafast Magic Angle Spinning Solid-State NMR Spectroscopy|journal=Accounts of Chemical Research|language=en|volume=50|issue=4|pages=1105–1113|doi=10.1021/acs.accounts.7b00082|issn=0001-4842|pmc=5828698|pmid=28353338}}</ref><ref>{{Cite journal|last1=Struppe|first1=Jochem|last2=Quinn|first2=Caitlin M.|last3=Sarkar|first3=Sucharita|last4=Gronenborn|first4=Angela M.|last5=Polenova|first5=Tatyana|date=2020-01-13|title=Ultrafast 1 H MAS NMR Crystallography for Natural Abundance Pharmaceutical Compounds|journal=Molecular Pharmaceutics|volume=17|issue=2|language=en|pages=674–682|doi=10.1021/acs.molpharmaceut.9b01157|issn=1543-8384|pmc=7307729|pmid=31891271}}</ref>

== Advanced solid-state NMR spectroscopy ==

=== Rotational Echo DOuble Resonance (REDOR) ===
[[File:Rotational Echo DOuble Resonance (REDOR) pulse sequence.png|thumb|Rotational Echo DOuble Resonance (REDOR) pulse sequence. The first excitation step (90º pulse or CP step) puts the magnetization in the transverse plane. Then two trains of 180º pulses synchronized with the rotor half-period are applied on the Y channel to reintroduce X-Y heteronuclear dipolar interactions. The trains of pulses are interrupted by a 180º pulse on the X channel that allows the refocussing of the X magnetization for the X-detection (spin echo). The delay between the 90º pulse and the beginning of the acquisition is referred to as the "rephrasing time".]]
Rotational Echo DOuble Resonance (REDOR) experiments,<ref name="REDOR">
{{cite journal
 |author = Gullion T.|author2 = Schaefer J.
 |date = 1989
 |title = Rotational-echo double-resonance NMR
 |journal = J. Magn. Reson.
 |volume = 81 |issue = 2
 |pages=196–200
 |pmid = 22152360
 |doi = 10.1016/j.jmr.2011.09.003
}}</ref><ref>{{Citation|last=Schaefer|first=Jacob|title=REDOR and TEDOR|date=2007-03-15|url=http://doi.wiley.com/10.1002/9780470034590.emrstm0448|encyclopedia=Encyclopedia of Magnetic Resonance|pages=emrstm0448|editor-last=Harris|editor-first=Robin K.|place=Chichester, UK|publisher=John Wiley & Sons, Ltd|language=en|doi=10.1002/9780470034590.emrstm0448|isbn=978-0-470-03459-0|access-date=2021-09-13}}</ref>  are a type of heteronuclear dipolar recoupling experiment which enables the re-introduction of heteronuclear dipolar couplings averaged by MAS.  The reintroduction of such dipolar coupling reduces the intensity of the NMR signal compared to a reference spectrum where no dephasing pulse is used.  REDOR can be used to measure heteronuclear distances, and are the basis of [[NMR crystallography|NMR crystallographic]] studies.

=== Ultra fast MAS for <sup>1</sup>H NMR ===

The strong <sup>1</sup>H-<sup>1</sup>H homonuclear dipolar interactions associated with broad NMR lines and short T<sub>2</sub> relaxation time effectively relegate proton for bimolecular NMR. Fast MAS and reduction of dipolar interactions by deuteration have made proton ssNMR as versatile as in solution. This includes spectral dispersion in multi-dimensional experiments<ref name=Protons>
{{cite journal
 |author = Linser R.|author2 = Fink U.|author3 = Reif B.
 |date = 2008
 |doi = 10.1016/j.jmr.2008.04.021
 |pmid = 18462963|title = Proton-Detected Scalar Coupling Based Assignment Strategies in MAS Solid-State NMR Spectroscopy Applied to Perdeuterated Proteins
 |journal = J. Magn. Reson.
 |volume = 193 |issue = 1|pages=89–93
 |bibcode = 2008JMagR.193...89L |hdl = 11858/00-001M-0000-0018-EE69-A|hdl-access = free}}</ref> and structurally valuable restraints and parameters important for studying material dynamics.<ref name=Dynamics>{{cite journal
 |author = Schanda, P.|author2 = Meier, B. H.|author3 = Ernst, M. 
 |date = 2010
 |doi = 10.1021/ja100726a
 |title = Quantitative Analysis of Protein Backbone Dynamics in Microcrystalline Ubiquitin by Solid-State NMR Spectroscopy
 |journal = J. Am. Chem. Soc. 
 |volume = 132 |issue = 45|pages=15957–15967
 |pmid=20977205
}}</ref>

Ultra-fast NMR and the sharpening of the NMR lines enable NMR pulse sequences to capitalize on proton-detection to improve the sensitivity of the experiments compared to the direct detection of a spin-1/2 system (X). Such enhancement factor <math>\xi</math> is given by:
: <math>\xi \propto \left(\frac{\gamma_H}{\gamma_X}\right)^{3/2} \left(\frac{W_X}{W_H}\right)^{1/2} \left(\frac{Q_H}{Q_X}\right)^{1/2}</math>
where <math>\gamma</math> are the [[Gyromagnetic ratio|gyromagnetic ratios]], <math>W</math> represent the NMR line widths, and <math>Q</math> represent the [[Q factor|quality factor]] of the probe resonances.<ref>{{Cite journal|last1=Ishii|first1=Yoshitaka|last2=Wickramasinghe|first2=Ayesha|last3=Matsuda|first3=Isamu|last4=Endo|first4=Yuki|last5=Ishii|first5=Yuji|last6=Nishiyama|first6=Yusuke|last7=Nemoto|first7=Takahiro|last8=Kamihara|first8=Takayuki|date=2018|title=Progress in proton-detected solid-state NMR (SSNMR): Super-fast 2D SSNMR collection for nano-mole-scale proteins|journal=Journal of Magnetic Resonance|language=en|volume=286|pages=99–109|doi=10.1016/j.jmr.2017.11.011|pmc=6387629|pmid=29223566|bibcode=2018JMagR.286...99I }}</ref>

=== MAS-Dynamic Nuclear Polarisation (MAS-DNP) ===
{{See|Dynamic nuclear polarization}}
Magic angle spinning dynamic nuclear polarization (MAS-DNP) is a technique that increases the sensitivity of NMR experiments by several orders of magnitude.<ref>{{Cite journal|last1=Lilly Thankamony|first1=Aany Sofia|last2=Wittmann|first2=Johannes J.|last3=Kaushik|first3=Monu|last4=Corzilius|first4=Björn|date=November 2017|title=Dynamic nuclear polarization for sensitivity enhancement in modern solid-state NMR|url=https://linkinghub.elsevier.com/retrieve/pii/S0079656517300201|journal=Progress in Nuclear Magnetic Resonance Spectroscopy|language=en|volume=102-103|pages=120–195|doi=10.1016/j.pnmrs.2017.06.002|pmid=29157490|doi-access=free}}</ref><ref name=":7">{{Cite journal|date=2019-09-01|title=Recent developments in MAS DNP-NMR of materials|url=https://www.sciencedirect.com/science/article/abs/pii/S092620401930030X|journal=Solid State Nuclear Magnetic Resonance|language=en|volume=101|pages=116–143|doi=10.1016/j.ssnmr.2019.05.009| arxiv=2007.09954|issn=0926-2040|last1=Rankin|first1=Andrew G.M.|last2=Trébosc|first2=Julien|last3=Pourpoint|first3=Frédérique|last4=Amoureux|first4=Jean-Paul|last5=Lafon|first5=Olivier|pmid=31189121|s2cid=189814925}}</ref> It involves transferring the very high electron polarisation from unpaired electrons to nearby nuclei. This is achieved at cryogenic temperatures through a continuous microwave irradiation from a [[klystron]] or a [[gyrotron]], with a frequency close to the corresponding [[electron paramagnetic resonance]] (EPR) frequency.

The development in the MAS-DNP instrumentation, and the improvement of polarising agents (TOTAPOL, AMUPOL, TEKPOL, etc.<ref name=":7" /> ) to achieve a more efficient transfer of polarisation has dramatically reduced experiments times which enabled the observation of surfaces,<ref>{{Cite journal|last1=Rossini|first1=Aaron J.|last2=Zagdoun|first2=Alexandre|last3=Lelli|first3=Moreno|last4=Lesage|first4=Anne|last5=Copéret|first5=Christophe|last6=Emsley|first6=Lyndon|date=2013-09-17|title=Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy|url=https://doi.org/10.1021/ar300322x|journal=Accounts of Chemical Research|volume=46|issue=9|pages=1942–1951|doi=10.1021/ar300322x|pmid=23517009|issn=0001-4842}}</ref> insensitive isotopes,<ref>{{Cite journal|last1=Perras|first1=Frédéric A.|last2=Kobayashi|first2=Takeshi|last3=Pruski|first3=Marek|date=2015-07-08|title=Natural Abundance 17 O DNP Two-Dimensional and Surface-Enhanced NMR Spectroscopy|url=https://pubs.acs.org/doi/10.1021/jacs.5b03905|journal=Journal of the American Chemical Society|language=en|volume=137|issue=26|pages=8336–8339|doi=10.1021/jacs.5b03905|pmid=26098846|osti=1227378|issn=0002-7863}}</ref> and multidimensional experiments on low natural abundance nuclei,<ref>{{Cite journal|last1=Smith|first1=Adam N.|last2=Märker|first2=Katharina|last3=Hediger|first3=Sabine|last4=De Paëpe|first4=Gaël|date=2019-08-15|title=Natural Isotopic Abundance 13 C and 15 N Multidimensional Solid-State NMR Enabled by Dynamic Nuclear Polarization|url=https://pubs.acs.org/doi/10.1021/acs.jpclett.8b03874|journal=The Journal of Physical Chemistry Letters|language=en|volume=10|issue=16|pages=4652–4662|doi=10.1021/acs.jpclett.8b03874|pmid=31361489|s2cid=199000068 |issn=1948-7185}}</ref> and diluted species.<ref>{{Cite journal|last1=Rossini|first1=Aaron J.|last2=Widdifield|first2=Cory M.|last3=Zagdoun|first3=Alexandre|last4=Lelli|first4=Moreno|last5=Schwarzwälder|first5=Martin|last6=Copéret|first6=Christophe|last7=Lesage|first7=Anne|last8=Emsley|first8=Lyndon|date=2014-02-12|title=Dynamic Nuclear Polarization Enhanced NMR Spectroscopy for Pharmaceutical Formulations|url=https://pubs.acs.org/doi/10.1021/ja4092038|journal=Journal of the American Chemical Society|language=en|volume=136|issue=6|pages=2324–2334|doi=10.1021/ja4092038|pmid=24410528|hdl=20.500.11850/80771 |issn=0002-7863|hdl-access=free}}</ref>

=== Beta-Detected Nuclear Magnetic Resonance (β-NMR) ===
Beta-detected nuclear magnetic resonance (β-NMR) is specialized technique that has working principles similar to [[muon spin spectroscopy]].<ref name=":1">{{Citation |last=Morris |first=Gerald D. |title=β-NMR |date=2013 |work=ISAC and ARIEL: The TRIUMF Radioactive Beam Facilities and the Scientific Program |pages=173–182 |url=http://dx.doi.org/10.1007/978-94-007-7963-1_19 |access-date=2024-11-29 |place=Dordrecht |publisher=Springer Netherlands |isbn=978-94-007-7962-4}}</ref> It is used in domains such as [[chemistry]], [[materials science]], [[condensed matter physics]], and [[biology]] as a powerful probe.<ref name=":1" /><ref>{{Cite journal |last=Abov |first=Yu. G. |last2=Gulko |first2=A. D. |last3=Dzheparov |first3=F. S. |date=2006 |title=Beta-NMR spectroscopy: Modern state and prospects |url=http://link.springer.com/10.1134/S106377880610005X |journal=Physics of Atomic Nuclei |language=en |volume=69 |issue=10 |pages=1701–1710 |doi=10.1134/S106377880610005X |issn=1063-7788}}</ref><ref name=":0">{{Cite journal |last=MacFarlane |first=W.A. |date=2015-06-21 |title=Implanted-ion βNMR: A new probe for nanoscience |url=https://linkinghub.elsevier.com/retrieve/pii/S0926204015000181 |journal=Solid State Nuclear Magnetic Resonance |language=en |volume=68-69 |pages=1–12 |doi=10.1016/j.ssnmr.2015.02.004}}</ref> β-NMR is practiced at facilities such as [[TRIUMF]] and [[ISOLDE]] as well as research groups in [[Osaka]] and [[Moscow]].<ref name=":0" />

What makes β-NMR different than conventional NMR is firstly, where and when the [[spin polarization]] of the nuclei occurs and secondly, how the signal is produced.<ref name=":1" /><ref name=":3">{{Cite journal |last=Gottberg |first=Alexander |last2=Stachura |first2=Monika |last3=Kowalska |first3=Magdalena |last4=Bissell |first4=Mark L. |last5=Arcisauskaite |first5=Vaida |last6=Blaum |first6=Klaus |last7=Helmke |first7=Alexander |last8=Johnston |first8=Karl |last9=Kreim |first9=Kim |last10=Larsen |first10=Flemming H. |last11=Neugart |first11=Rainer |last12=Neyens |first12=Gerda |last13=Garcia Ruiz |first13=Ronald F. |last14=Szunyogh |first14=Daniel |last15=Thulstrup |first15=Peter W. |date=2014-10-09 |title=Billion-Fold Enhancement in Sensitivity of Nuclear Magnetic Resonance Spectroscopy for Magnesium Ions in Solution |url=http://dx.doi.org/10.1002/cphc.201402619 |journal=ChemPhysChem |volume=15 |issue=18 |pages=3929–3932 |doi=10.1002/cphc.201402619 |issn=1439-4235}}</ref> To conduct a β-NMR experiment, [[optical pumping]] is performed on a [[Radioactive decay|radioactive]] beam of particles, such as <sup>8</sup>Li and <sup>31</sup>Mg, to polarize their nuclear spin to nearly one-hundred percent.<ref name=":1" /><ref name=":2">{{Cite journal |last=Levy |first=C. D. P. |last2=Pearson |first2=M. R. |last3=Dehn |first3=M. H. |last4=Karner |first4=V. L. |last5=Kiefl |first5=R. F. |last6=Lassen |first6=J. |last7=Li |first7=R. |last8=MacFarlane |first8=W. A. |last9=McFadden |first9=R. M. L. |last10=Morris |first10=G. D. |last11=Stachura |first11=M. |last12=Teigelhöfer |first12=A. |last13=Voss |first13=A. |date=2016-11-22 |title=Development of a polarized 31Mg+ beam as a spin-1/2 probe for BNMR |url=https://link.springer.com/article/10.1007/s10751-016-1372-8 |journal=Hyperfine Interactions |language=en |volume=237 |issue=1 |pages=162 |doi=10.1007/s10751-016-1372-8 |issn=1572-9540}}</ref> The [[Isotope|isotopes]] are subsequently implanted into a sample [[Vacuum|in vacuum]] in the dilute-limit to eliminate homonuclear probe interactions. The [[spin–lattice relaxation]] of the probe is monitored by the [[Parity (physics)|parity-violating]] [[Beta decay|beta-decay]] of the radioactive isotope.<ref name=":1" /><ref name=":2" /> This [[Anisotropy|anisotropic]] decay is where the signal originates for β-NMR experiment.<ref name=":1" /><ref name=":3" /> This technique allows for investigation of the local magnetic and electronic environment within a material .<ref name=":1" /><ref name=":2" />

== Applications ==
ssNMR spectroscopy serves as an effective analytical tool in biological, organic, and inorganic chemistry due to its close resemblance to liquid-state spectra while providing additional insights into anisotropic interactions.<ref>{{cite journal |last1=Laws |first1=David D. Laws |last2=Bitter |first2=Hans-Marcus L. |last3=Jerschow |first3=Alexej  |title=Solid-State NMR Spectroscopic Methods in Chemistry |journal=Angewandte Chemie |volume=41 |issue=17 |pages=3096 |date=30 August 2002 |doi=10.1002/1521-3773(20020902)41:17<3096::AID-ANIE3096>3.0.CO;2-X |url=https://onlinelibrary.wiley.com/doi/10.1002/1521-3773(20020902)41:17%3C3096::AID-ANIE3096%3E3.0.CO;2-X |doi-access=free}}</ref>

It is used to characterize chemical composition, structure, local motions, kinetics, and thermodynamics, with the special ability to assign the observed behavior to specific sites in a molecule. It is also crucial in the area of [[Surface science|surface]] and interfacial chemistry.<ref>{{cite journal| last1= Marchetti| first1= Alessandro| last2= Chen| first2= Juner| last3= Pang| first3= Zhenfeng| last4 = Li| first4= Shenhui| last5= Ling| first5= Daishun| last6= Deng| first6= Feng| last7= Kong| first7= Xueqian| title= Understanding Surface and Interfacial Chemistry in Functional Nanomaterials via Solid-State NMR| journal= Advanced Materials| volume = 29| issue= 14 |pages= 1605895| date= April 11, 2017| doi= 10.1002/adma.201605895| url=https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.201605895 |access-date =20 December 2023}}</ref>

=== Biology and Medicine ===
==== Proteins and bioaggregates ====
ssNMR is used to study insoluble proteins and proteins such as [[Membrane protein|membrane proteins]]<ref>{{Cite journal |last=McDermott |first=Ann |date=June 2009 |title=Structure and Dynamics of Membrane Proteins by Magic Angle Spinning Solid-State NMR |url=http://www.annualreviews.org/doi/10.1146/annurev.biophys.050708.133719 |journal=Annual Review of Biophysics |language=en |volume=38 |issue=1 |pages=385–403 |doi=10.1146/annurev.biophys.050708.133719 |issn=1936-122X |pmid=19245337}}</ref> and [[amyloid]] [[Fibril|fibrils]].<ref>{{Cite journal |last=Tycko |first=Robert |date=2011-05-05 |title=Solid-State NMR Studies of Amyloid Fibril Structure |journal=Annual Review of Physical Chemistry |language=en |volume=62 |issue=1 |pages=279–299 |bibcode=2011ARPC...62..279T |doi=10.1146/annurev-physchem-032210-103539 |issn=0066-426X |pmc=3191906 |pmid=21219138}}</ref> Using the principles of MAS, [[protein tertiary structure]] information can be determined.<ref>{{Cite journal |last1=Linser |first1=Rasmus |last2=Bardiaux |first2=Benjamin |last3=Higman |first3=Victoria |last4=Fink |first4=Uwe |last5=Reif |first5=Bernd |date=March 2011 |title=Structure Calculation from Unambiguous Long-Range Amide and Methyl 1H-1H Distance Restraints for a Microcrystalline Protein with MAS Solid-State NMR Spectroscopy |url=https://pubs.acs.org/doi/10.1021/ja110222h |journal=J. Am. Chem. Soc. |language=en |volume=133 |pages=5905-5912 |doi=10.1021/ja110222h |hdl-access=free |hdl=11858/00-001M-0000-0018-E916-0}}</ref> This includes the assessment of protein dynamics.<ref>{{Cite journal |last1=Schanda |first1=Paul |last2=Ernst |first2=Matthias |date=August 2016 |title=Studying dynamics by magic-angle spinning solid-state NMR spectroscopy: Principles and applications to biomolecules |url=https://www.sciencedirect.com/science/article/abs/pii/S0079656516000078?via%3Dihub |journal=Prog. Nucl. Magn. Reson. Spectrosc. |language=en |volume=96 |pages=1-46 |doi=10.1016/j.pnmrs.2016.02.001 |pmc=4836562}}</ref>

==== Biomaterials ====
ssNMR is used to study biomaterials such as [[bone]],<ref>{{Cite book|url=https://www.worldcat.org/oclc/56697027|title=New techniques in solid-state NMR|date=2005|publisher=Springer|others=Jacek Klinowski|isbn=978-3-540-22168-5|location=Berlin|oclc=56697027}}</ref><ref>{{Cite journal|last=Duer|first=Melinda J.|date=2015|title=The contribution of solid-state NMR spectroscopy to understanding biomineralization: Atomic and molecular structure of bone|url=https://linkinghub.elsevier.com/retrieve/pii/S1090780714003590|journal=Journal of Magnetic Resonance|language=en|volume=253|pages=98–110|doi=10.1016/j.jmr.2014.12.011|pmid=25797009|bibcode=2015JMagR.253...98D }}</ref> [[teeth]],<ref>{{Cite journal |last1=Mohammed |first1=N.R. |last2=Kent |first2=N.W. |last3=Lynch |first3=R.J.M. |last4=Karpukhina |first4=N. |last5=Hill |first5=R. |last6=Anderson |first6=P. |date=2013 |title=Effects of Fluoride on in vitro Enamel Demineralization Analyzed by 19F MAS-NMR |url=https://www.karger.com/Article/FullText/350171 |journal=Caries Research |language=en |volume=47 |issue=5 |pages=421–428 |doi=10.1159/000350171 |pmid=23712030 |s2cid=6854002 |issn=0008-6568}}</ref><ref>{{Cite journal |last1=Ferizoli |first1=Bajram |last2=Cresswell-Boyes |first2=Alexander J. |last3=Anderson |first3=Paul |last4=Lynch |first4=Richard J. M. |last5=Hill |first5=Robert G. |date=2023-05-24 |title=Effects of fluoride on in vitro hydroxyapatite demineralisation analysed by 19F MAS-NMR |journal=Frontiers in Dental Medicine |volume=4 |doi=10.3389/fdmed.2023.1171827 |issn=2673-4915 |doi-access=free |pmc=11797780 }}</ref> [[hair]],<ref>{{Cite journal|last1=Kricheldorf|first1=H. R.|last2=Müller|first2=D.|date=1984-11-01|title=Secondary structure of peptides 16th. Characterization of proteins by means of13C NMR CP/MAS spectroscopy|url=https://doi.org/10.1007/BF01452215|journal=Colloid and Polymer Science|language=en|volume=262|issue=11|pages=856–861|doi=10.1007/BF01452215|s2cid=95774717|issn=1435-1536}}</ref> [[silk]],<ref>{{Cite journal|date=2001-12-14|title=Structure of Silk studied with NMR|url=https://www.sciencedirect.com/science/article/abs/pii/S0079656501000395|journal=Progress in Nuclear Magnetic Resonance Spectroscopy|language=en|volume=39|issue=4|pages=301–352|doi=10.1016/S0079-6565(01)00039-5|issn=0079-6565|last1=Zhao|first1=Chenhua|last2=Asakura|first2=Tetsuo}}</ref> [[wood]],<ref>{{Citation|last1=Gil|first1=A.M.|title=Solid-State Nmr Studies Of Wood And Other Lignocellulosic Materials|date=1999|url=https://linkinghub.elsevier.com/retrieve/pii/S0066410308600149|work=Annual Reports on NMR Spectroscopy|volume=37|pages=75–117|publisher=Elsevier|language=en|doi=10.1016/s0066-4103(08)60014-9|isbn=978-0-12-505337-2|access-date=2021-09-13|last2=Neto|first2=C. Pascoal}}</ref> as well as [[Virus|viruses]],<ref>{{Cite journal|last1=Quinn|first1=Caitlin M.|last2=Lu|first2=Manman|last3=Suiter|first3=Christopher L.|last4=Hou|first4=Guangjin|last5=Zhang|first5=Huilan|last6=Polenova|first6=Tatyana|date=2015|title=Magic angle spinning NMR of viruses|journal=Progress in Nuclear Magnetic Resonance Spectroscopy|language=en|volume=86-87|pages=21–40|doi=10.1016/j.pnmrs.2015.02.003|pmc=4413014|pmid=25919197}}</ref><ref>{{Cite journal|last1=Mandala|first1=Venkata S.|last2=McKay|first2=Matthew J.|last3=Shcherbakov|first3=Alexander A.|last4=Dregni|first4=Aurelio J.|last5=Kolocouris|first5=Antonios|last6=Hong|first6=Mei|date=2020|title=Structure and drug binding of the SARS-CoV-2 envelope protein transmembrane domain in lipid bilayers|journal=Nature Structural & Molecular Biology|language=en|volume=27|issue=12|pages=1202–1208|doi=10.1038/s41594-020-00536-8|issn=1545-9993|pmc=7718435|pmid=33177698}}</ref> [[Plant|plants]],<ref>{{Cite journal|last1=Wang|first1=Tuo|last2=Hong|first2=Mei|date=2016|title=Solid-state NMR investigations of cellulose structure and interactions with matrix polysaccharides in plant primary cell walls|journal=Journal of Experimental Botany|language=en|volume=67|issue=2|pages=503–514|doi=10.1093/jxb/erv416|issn=0022-0957|pmc=6280985|pmid=26355148}}</ref><ref>{{Cite journal|last1=Zhao|first1=Wancheng|last2=Fernando|first2=Liyanage D.|last3=Kirui|first3=Alex|last4=Deligey|first4=Fabien|last5=Wang|first5=Tuo|date=2020|title=Solid-state NMR of plant and fungal cell walls: A critical review|url=https://linkinghub.elsevier.com/retrieve/pii/S0926204020300229|journal=Solid State Nuclear Magnetic Resonance|language=en|volume=107|pages=101660|doi=10.1016/j.ssnmr.2020.101660|pmid=32251983|s2cid=215409770 }}</ref> [[Cell (biology)|cells]],<ref>{{Cite journal|last1=Renault|first1=M.|last2=Tommassen-van Boxtel|first2=R.|last3=Bos|first3=M. P.|last4=Post|first4=J. A.|last5=Tommassen|first5=J.|last6=Baldus|first6=M.|date=2012-03-27|title=Cellular solid-state nuclear magnetic resonance spectroscopy|journal=Proceedings of the National Academy of Sciences|language=en|volume=109|issue=13|pages=4863–4868|doi=10.1073/pnas.1116478109|issn=0027-8424|pmc=3323964|pmid=22331896|doi-access=free}}</ref><ref>{{Cite journal|last1=Renault|first1=Marie|last2=Pawsey|first2=Shane|last3=Bos|first3=Martine P.|last4=Koers|first4=Eline J.|last5=Nand|first5=Deepak|last6=Tommassen-van Boxtel|first6=Ria|last7=Rosay|first7=Melanie|last8=Tommassen|first8=Jan|last9=Maas|first9=Werner E.|last10=Baldus|first10=Marc|date=2012-03-19|title=Solid-State NMR Spectroscopy on Cellular Preparations Enhanced by Dynamic Nuclear Polarization|url=https://onlinelibrary.wiley.com/doi/10.1002/anie.201105984|journal=Angewandte Chemie International Edition|language=en|volume=51|issue=12|pages=2998–3001|doi=10.1002/anie.201105984|pmid=22298470}}</ref> and collected [[Biopsy|biopsies]].<ref>{{Cite journal|last1=Martínez-Bisbal|first1=M. Carmen|last2=Martí-Bonmatí|first2=Luis|last3=Piquer|first3=José|last4=Revert|first4=Antonio|last5=Ferrer|first5=Pilar|last6=Llácer|first6=José L.|last7=Piotto|first7=Martial|last8=Assemat|first8=Olivier|last9=Celda|first9=Bernardo|date=2004|title=1H and13C HR-MAS spectroscopy of intact biopsy samplesex vivo andin vivo1H MRS study of human high grade gliomas|url=https://onlinelibrary.wiley.com/doi/10.1002/nbm.888|journal=NMR in Biomedicine|language=en|volume=17|issue=4|pages=191–205|doi=10.1002/nbm.888|pmid=15229932|s2cid=19939314|issn=0952-3480}}</ref>

==== Drugs and drug delivery systems ====
ssNMR is used in pharmaceutical research for the characterization of drug [[Polymorphism (biology)|polymorphs]] and solid dispersions.<ref>{{Cite journal |last1=Li |first1=Mingyue |last2=Xu |first2=Wei |last3=Su |first3=Yongchao |last4=Su |first4=Yongchao |date=December 2020 |title=Solid-state NMR Spectroscopy in Pharmaceutical Sciences |journal=TrAC Trends in Analytical Chemistry |volume=135 |issue=4 |pages=116152 |doi=10.1016/j.trac.2020.116152 |doi-access=free}}</ref>

=== Materials science ===

ssNMR spectroscopy is used in materials science to analyze solid samples.<ref>{{cite journal |doi=10.1039/D0SC00735H |last1=Brunner |first1=Eike |last2=Rauche |first2=Marcus |date=2020 |title=Solid-state NMR spectroscopy: an advancing tool to analyse the structure and properties of metal-organic frameworks |journal=Chemical Science |volume=11 |issue=6 |pages=9880–9891|pmc=8159446 }}</ref> Here, molecules have restricted motion which leads to complex magnetic interactions, such as dipole-dipole coupling, chemical shift anisotropy, and quadrupolar interactions.<ref>Borisov, A.S., Hazendonk, P. & Hayes, P.G. Solid-State Nuclear Magnetic Resonance Spectroscopy: A Review of Modern Techniques and Applications for Inorganic Polymers. ''J Inorg Organomet Polym'' 20, 183–212 (2010). <nowiki>https://doi.org/10.1007/s10904-010-9358-5</nowiki></ref> These interactions can provide more detailed information than [[X-ray diffraction]] or [[Nuclear magnetic resonance spectroscopy|solution NMR spectroscopy]] about the material's structure to elucidate information on the solid's (crystalline and non-crystalline) local structure and dynamics.

ssNMR has been successfully used to study [[Metal–organic framework|metal organic frameworks]],<ref>{{Cite journal |last1=Hoffmann |first1=Herbert |last2=Debowski |first2=Marta |last3=Müller |first3=Philipp |last4=Paasch |first4=Silvia |last5=Senkovska |first5=Irena |last6=Kaskel |first6=Stefan |last7=Brunner |first7=Eike |date=2012-11-28 |title=Solid-State NMR Spectroscopy of Metal–Organic Framework Compounds (MOFs) |journal=Materials |language=en |volume=5 |issue=12 |pages=2537–2572 |bibcode=2012Mate....5.2537H |doi=10.3390/ma5122537 |issn=1996-1944 |pmc=5449066 |doi-access=free}}</ref> [[Electric battery|solid-state batteries]], <ref>{{Cite journal |last1=Blanc |first1=Frédéric |last2=Leskes |first2=Michal |last3=Grey |first3=Clare P. |date=2013-09-17 |title=In Situ Solid-State NMR Spectroscopy of Electrochemical Cells: Batteries, Supercapacitors, and Fuel Cells |url=https://pubs.acs.org/doi/10.1021/ar400022u |journal=Accounts of Chemical Research |language=en |volume=46 |issue=9 |pages=1952–1963 |doi=10.1021/ar400022u |issn=0001-4842 |pmid=24041242}}</ref> surfaces of [[nanoporous materials]],<ref>{{Cite journal |last1=Pinto |first1=Moisés L. |last2=Mafra |first2=Luís |last3=Guil |first3=José M. |last4=Pires |first4=João |last5=Rocha |first5=João |date=2011-03-22 |title=Adsorption and Activation of CO 2 by Amine-Modified Nanoporous Materials Studied by Solid-State NMR and 13 CO 2 Adsorption |url=https://pubs.acs.org/doi/10.1021/cm1029563 |journal=Chemistry of Materials |language=en |volume=23 |issue=6 |pages=1387–1395 |doi=10.1021/cm1029563 |issn=0897-4756}}</ref> and [[Polymer|polymers]].<ref>{{Cite book |last=Schmidt-Rohr |first=K. |url=https://www.worldcat.org/oclc/31785818 |title=Multidimensional solid-state NMR and polymers |date=1994 |publisher=Academic Press |others=Hans Wolfgang Spiess |isbn=0-12-626630-1 |location=London |oclc=31785818}}</ref>

== References ==
{{reflist}}

=== Suggested readings for beginners ===

==== General NMR ====

* {{Cite web|last=Keeler|first=James|date=2002|others=Apollo-University Of Cambridge Repository, Apollo-University Of Cambridge Repository|title=Understanding NMR Spectroscopy|url=https://www.repository.cam.ac.uk/handle/1810/257040|language=en|doi=10.17863/CAM.968}}
* {{Cite book|last=Hore|first=P. J.|url=https://www.worldcat.org/oclc/910929523|title=NMR : the toolkit : how pulse sequences work|date=2015|others=J. A. Jones, Stephen Wimperis|isbn=978-0-19-870342-6|edition=2nd|location=Oxford|oclc=910929523}}
* {{Cite book|last=Hore|first=P. J.|url=https://www.worldcat.org/oclc/910929524|title=Nuclear magnetic resonance|date=2015|isbn=978-0-19-870341-9|edition=2nd|location=Oxford|oclc=910929524}}
*{{Cite book|url=https://www.worldcat.org/oclc/796758664|title=Encyclopedia of NMR|date=2012|publisher=John Wiley & Sons|others=Robin K. Harris, Roderick E. Wasylishen|isbn=978-0-470-05821-3|location=Chichester, West Sussex|oclc=796758664}}

==== Solid-state NMR ====
* {{cite journal | author = Laws David D., Hans- , Bitter Marcus L., Jerschow Alexej | year = 2002 | title = Solid-State NMR Spectroscopic Methods in Chemistry | journal = Angewandte Chemie International Edition | volume = 41 | issue = 17| pages = 3096–3129 | doi = 10.1002/1521-3773(20020902)41:17<3096::AID-ANIE3096>3.0.CO;2-X | pmid = 12207374  }}
* {{cite journal |doi=10.1038/s43586-020-00002-1|title=Solid-state NMR spectroscopy|year=2021|last1=Reif|first1=Bernd|last2=Ashbrook|first2=Sharon E.|last3=Emsley|first3=Lyndon|last4=Hong|first4=Mei|journal=Nature Reviews Methods Primers|volume=1|pmid=34368784|pmc=8341432}}
* Levitt, Malcolm H., ''Spin Dynamics: Basics of Nuclear Magnetic Resonance'', Wiley, Chichester, United Kingdom, 2001. {{ISBN|978-0470511176}} (NMR basics, including solids)
* [[Melinda Duer|Duer, Melinda J.]], ''Introduction to Solid-State NMR Spectroscopy'', Blackwell, Oxford, 2004. (Some detailed examples of ssNMR spectroscopy)
* Schmidt-Rohr, K. and Spiess, H.-W., ''Multidimensional Solid-State NMR and Polymers'', Academic Press, San Diego, 1994.

== External links ==
* [https://mrsimulator.readthedocs.io mrsimulator] Python package for simulating solid-state NMR spectra.
* [http://ssnmr.blogspot.com/ SSNMRBLOG] Solid-State NMR Literature Blog by Prof. Rob Schurko's Solid-State NMR group at the University of Windsor
* {{Cite web|title=Solid-State MAS NMR {{!}} Protein NMR|url=https://www.protein-nmr.org.uk/solid-state-mas-nmr/|access-date=2021-09-13|language=en-US}} 
* {{Cite web|title=University of Ottawa NMR Facility Blog|url=http://u-of-o-nmr-facility.blogspot.com|access-date=2021-09-13|website=u-of-o-nmr-facility.blogspot.com}} 

{{BranchesofSpectroscopy}}
{{NMR by isotope}}

[[Category:Nuclear magnetic resonance]]
[[Category:Scientific techniques]]