Solid-state nuclear magnetic resonance

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Solid-state 900 MHz (21.1 T ) NMR spectrometer at the Canadian National Ultrahigh-field NMR Facility for Solids 900 magnet new.jpg
Solid-state 900 MHz (21.1 T ) NMR spectrometer at the Canadian National Ultrahigh-field NMR Facility for Solids

Solid-state NMR (ssNMR) spectroscopy is a technique for characterizing atomic level structure in solid materials e.g. powders, single crystals and amorphous samples and tissues using nuclear magnetic resonance (NMR) spectroscopy. The anisotropic part of many spin interactions are present in solid-state NMR, unlike in solution-state NMR where rapid tumbling motion averages out many of the spin interactions. As a result, solid-state NMR spectra are characterised by larger linewidths than in solution state NMR, which can be utilized to give quantitative information on the molecular structure, conformation and dynamics of the material. Solid-state NMR is often combined with magic angle spinning to remove anisotropic interactions and improve the resolution as well as the sensitivity of the technique.

Contents

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) MAS rotors.jpg
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

The resonance frequency of a nuclear spin depends on the strength of the magnetic field at the nucleus, which can be modified by isotropic (e.g. chemical shift, isotropic J-coupling) and anisotropic interactions (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

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

Vectors important for dipolar coupling between nuclear spins I1 and I2. th is the angle between the vector connecting I1 and I2, and the magnetic field B. SSNMR dip coupl vect.png
Vectors important for dipolar coupling between nuclear spins I1 and I2. θ is the angle between the vector connecting I1 and I2, and the magnetic field B.

Nuclear spins exhibit a 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,

,

where γ1 and γ2 are the gyromagnetic ratios of the nuclei, is the reduced Planck constant, and 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

.

D becomes zero for . Consequently, two nuclei with a dipolar coupling vector at an angle of θm = 54.7° to a strong external magnetic field have zero dipolar coupling. θm is called the magic angle. Magic angle spinning is typically used to remove dipolar couplings weaker than the spinning rate.

Quadrupolar interaction

Nuclei with a spin quantum number >1/2 have a non-spherical charge distribution and an associated electric quadrupole moment tensor. The nuclear electric quadrupole moment couples with surrounding electric field gradients. The nuclear quadrupole coupling is one of the largest interactions in NMR spectroscopy, often comparable in size to the Zeeman coupling. 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 and levels are unaffected by the first-order frequency contribution. The second-order frequency contribution depends on the P4 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 DAS (Double Angle Spinning) [2] 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. [3] [4] 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

Paramagnetic substances are subject to the Knight shift.

Solid-state NMR line shapes

Powder pattern

Simulations of the shape of different powder patterns for different asymmetry
e
{\displaystyle \eta }
and chemical shift anisotropy
D
C
S
{\displaystyle \Delta _{CS}}
parameters. Powder pattern.svg
Simulations of the shape of different powder patterns for different asymmetry and chemical shift anisotropy 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 , the chemical shift anisotropy parameter , and the asymmetry parameter . [5]

Dipolar pattern

Dipolar powder pattern (Pake pattern) Simulation of a dipolar coupling powder pattern in a heteronuclear two spin system.svg
Dipolar powder pattern (Pake pattern)

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 .: [6]

where γ1 and γ2 are the gyromagnetic ratios of the dipolar-coupled nuclei, is the internuclear distance, is the reduced Planck constant, and is the vacuum permeability.

Essential solid-state techniques

Magic angle spinning

Simulation of an increasing MAS rate on the C solid-state NMR spectrum of C-Glycine at 9.4 T (400 MHz H frequency). MAS introduces a set of spinning sidebands separated from the isotropic frequency by a multiple of the spinning rate. Glycine 13C 9.4T MAS 20khz.gif
Simulation of an increasing MAS rate on the C solid-state NMR spectrum of C-Glycine at 9.4 T (400 MHz 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 solid-state NMR to produce narrower NMR and more intense NMR lines. This is achieved by rotating the sample at the magic angle θm (ca. 54.74°, where cos2θm = 1/3) with respect to the direction of the magnetic field, which has the effect to cancel, at least partially, anisotropic nuclear interactions such as dipolar, chemical shift anisotropy, and quadrupolar interactions. 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.

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. 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-polarisation

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 H decoupling. Cross-polarization.png
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 H decoupling.

Cross-polarization (CP) if a fundamental 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. 13
C
, 15
N
) by magnetization transfer from an abundant nuclei with a high gyromagnetic ratio (e.g. 1
H
), or as a spectral editing method to get through space information (e.g. directed 15
N
13
C
CP in protein spectroscopy).

To establish magnetization transfer, RF pulses ("contact pulses") are simultaneously applied on both frequency channels to produce fields whose strength fulfil the Hartmann–Hahn condition: [7] [8]

where are the gyromagnetic ratios, is the spinning rate, and 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 (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 1H. The irradiation can be continuous (continuous wave decoupling [9] ), or a series of pulses that extend the performance and the bandwidth of the decoupling (TPPM, [10] SPINAL-64, [11] SWf-TPPM [12] )

Homonuclear decoupling is achieved with multiple-pulse sequences (WAHUHA, [13] MREV-8, [14] BR-24, [15] BLEW-12, [16] FSLG [17] ), or continuous wave modulation (DUMBO, [18] eDUMBO [19] ). Dipolar interactions can also be removed with magic angle spinning. Ultra fast MAS (from 60 kHz up to above 111 kHz) is an efficient way to average all dipolar interactions, including 1H–1H homonuclear dipolar interactions, which extends the resolution of 1H spectra and enables the usage of pulse sequences used in solution state NMR. [20] [21]

Advanced solid-state NMR spectroscopy

Rotational Echo DOuble Resonance (REDOR)

Rotational Echo DOuble Resonance (REDOR) pulse sequence. The first excitation step (90o pulse or CP step) puts the magnetisation in the transverse plane. Then two trains of 180o pulses synchronised 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 magnetisation 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) pulse sequence.png
Rotational Echo DOuble Resonance (REDOR) pulse sequence. The first excitation step (90º pulse or CP step) puts the magnetisation in the transverse plane. Then two trains of 180º pulses synchronised 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 magnetisation 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) experiment, [22] [23] are a type of heteronuclear dipolar recoupling experiment which enable one to re-introduce heteronuclear dipolar couplings averaged by MAS. The reintroduction of such dipolar coupling reduce the intensity of the NMR signal intensity 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 crystallographic studies.

Ultra Fast MAS for 1H NMR

The strong 1H-1H homonuclear dipolar interactions associated with broad NMR lines and short T2 relaxation time effectively relegate proton for bimolecular NMR. Recent developments of faster 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 [24] as well as structurally valuable restraints and parameters important for studying material dynamics. [25]

Ultra-fast NMR and the associated sharpening of the NMR lines enables 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 is given by:

where are the gyromagnetic ratios, represent the NMR line widths, and represent the quality factor of the probe resonances. [26]

MAS-Dynamic Nuclear Polarisation (MAS-DNP)

Magic angle spinning dynamic nuclear polarization (MAS-DNP) is a technique that increases the sensitivity of NMR experiments by several orders of magnitude. [27] [28] It involves the transfer of the very high electron polarisation from unpaired electrons to nearby nuclei. This is achieved at cryogenic temperatures by the means of a continuous microwave irradiation coming 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, as well as the improvement of polarising agents (TOTAPOL, AMUPOL, TEKPOL, etc. [29] ) to achieve a more efficient transfer of polarisation has dramatically reduced experiments times which enabled the observation of surfaces, [30] insensitive isotopes, [31] and multidimensional experiments on low natural abundance nuclei, [32] and diluted species. [33]

Applications

Solid-state NMR 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. [34]

It is used to characterize chemical composition, supramolecular 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 and interfacial chemistry. [35]

Biology and Medicine

Proteins and bioaggregates

Solid-state NMR is used to study insoluble proteins and proteins very sensitive to their environment such as membrane proteins [36] and amyloid fibrils. [37] The latter topic relates to protein aggregation diseases such as Alzheimer's disease and Parkinson's disease. Solid-state NMR spectroscopy complements solution-state NMR spectroscopy and beam diffraction methods (e.g. X-ray crystallography, electron microscopy). Despite often requiring isotopic enrichment, [38] ssNMR has the advantage that little sample preparation is required and can be used on not just dry or frozen samples, but also fully hydrated samples or native non-crystalline tissues. [39] Solid-state NMR structure elucidation of proteins has traditionally been based on secondary chemical shifts and spatial contacts between nuclei.

Biomaterials

Solid-state NMR has also been successfully used to study biomaterials such as bone, [40] [41] teeth, [42] [43] hair, [44] silk, [45] wood, [46] as well as viruses, [47] [48] plants, [49] [50] cells, [51] [52] biopsies, [53] and even live animals. [54]

Drugs and drug delivery systems

Other ssNMR applications are in the field of pharmaceutical research. [55]

Firstly, it plays a pivotal role in the characterizatio of drug polymorphs and solid dispersions. This is useful to minimize risks linked with solid-state form changes: the determination of the solid form of an active pharmaceutical ingredient plays a pivotal role in ensuring controlled bioavailability and stability; alterations can impact the efficacy of drugs profoundly. Analysis of molecular-level interactions facilitates also the formulation development of amorphous solid dispersions, targeting enhanced solubility.

Furthermore, ssNMR aids in characterizing porous materials tailored for drug delivery systems, thus enhabling scientists to design carriers and formulations that heighten drug efficacy. [56]

Materials science

Solid-state NMR has been successfully used to study metal organic frameworks (MOFS), [57] batteries, [58] [59] [60] surfaces of nanoporous materials, [61] polymers. [62]

Art conservation

NMR can also be applied to art conservation. Different salts and moisture levels can be detected through the use of solid state NMR. However, sampling sizes retrieved from works of art in order to run through these large conducting magnets typically exceed levels deemed acceptable. Unilateral NMR techniques use portable magnets that are applied to the object of interest, bypassing the need for sampling. [63]

Related Research Articles

The nuclear Overhauser effect (NOE) is the transfer of nuclear spin polarization from one population of spin-active nuclei to another via cross-relaxation. A phenomenological definition of the NOE in nuclear magnetic resonance spectroscopy (NMR) is the change in the integrated intensity of one NMR resonance that occurs when another is saturated by irradiation with an RF field. The change in resonance intensity of a nucleus is a consequence of the nucleus being close in space to those directly affected by the RF perturbation.

Dynamic nuclear polarization (DNP) results from transferring spin polarization from electrons to nuclei, thereby aligning the nuclear spins to the extent that electron spins are aligned. Note that the alignment of electron spins at a given magnetic field and temperature is described by the Boltzmann distribution under the thermal equilibrium. It is also possible that those electrons are aligned to a higher degree of order by other preparations of electron spin order such as: chemical reactions, optical pumping and spin injection. DNP is considered one of several techniques for hyperpolarization. DNP can also be induced using unpaired electrons produced by radiation damage in solids.

In nuclear magnetic resonance (NMR) spectroscopy, the chemical shift is the resonant frequency of an atomic nucleus relative to a standard in a magnetic field. Often the position and number of chemical shifts are diagnostic of the structure of a molecule. Chemical shifts are also used to describe signals in other forms of spectroscopy such as photoemission spectroscopy.

<span class="mw-page-title-main">Nuclear magnetic resonance spectroscopy</span> Laboratory technique

Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy or magnetic resonance spectroscopy (MRS), is a spectroscopic technique based on re-orientation of atomic nuclei with non-zero nuclear spins in an external magnetic field. This re-orientation occurs with absorption of electromagnetic radiation in the radio frequency region from roughly 4 to 900 MHz, which depends on the isotopic nature of the nucleus and increased proportionally to the strength of the external magnetic field. Notably, the resonance frequency of each NMR-active nucleus depends on its chemical environment. As a result, NMR spectra provide information about individual functional groups present in the sample, as well as about connections between nearby nuclei in the same molecule. As the NMR spectra are unique or highly characteristic to individual compounds and functional groups, NMR spectroscopy is one of the most important methods to identify molecular structures, particularly of organic compounds.

<span class="mw-page-title-main">Magic angle spinning</span>

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 at the magic angle θm with respect to the direction of the magnetic field.

<span class="mw-page-title-main">Electron paramagnetic resonance</span> Technique to study materials that have unpaired electrons

Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials that have unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but the spins excited are those of the electrons instead of the atomic nuclei. EPR spectroscopy is particularly useful for studying metal complexes and organic radicals. EPR was first observed in Kazan State University by Soviet physicist Yevgeny Zavoisky in 1944, and was developed independently at the same time by Brebis Bleaney at the University of Oxford.

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, P2(cos θ) = 0, and so any interaction which depends on this second-order Legendre polynomial vanishes at the magic angle. This property makes the magic angle of particular importance in magic angle spinning solid-state NMR spectroscopy. In magnetic resonance imaging, structures with ordered collagen, such as tendons and ligaments, oriented at the magic angle may appear hyperintense in some sequences; this is called the magic angle artifact or effect.

Nuclear magnetic resonance spectroscopy of proteins is a field of structural biology in which NMR spectroscopy is used to obtain information about the structure and dynamics of proteins, and also nucleic acids, and their complexes. The field was pioneered by Richard R. Ernst and Kurt Wüthrich at the ETH, and by Ad Bax, Marius Clore, Angela Gronenborn at the NIH, and Gerhard Wagner at Harvard University, among others. Structure determination by NMR spectroscopy usually consists of several phases, each using a separate set of highly specialized techniques. The sample is prepared, measurements are made, interpretive approaches are applied, and a structure is calculated and validated.

<span class="mw-page-title-main">Nuclear magnetic resonance quantum computer</span> Proposed spin-based quantum computer implementation

Nuclear magnetic resonance quantum computing (NMRQC) is one of the several proposed approaches for constructing a quantum computer, that uses the spin states of nuclei within molecules as qubits. The quantum states are probed through the nuclear magnetic resonances, allowing the system to be implemented as a variation of nuclear magnetic resonance spectroscopy. NMR differs from other implementations of quantum computers in that it uses an ensemble of systems, in this case molecules, rather than a single pure state.

In nuclear chemistry and nuclear physics, J-couplings are mediated through chemical bonds connecting two spins. It is an indirect interaction between two nuclear spins that arises from hyperfine interactions between the nuclei and local electrons. In NMR spectroscopy, J-coupling contains information about relative bond distances and angles. Most importantly, J-coupling provides information on the connectivity of chemical bonds. It is responsible for the often complex splitting of resonance lines in the NMR spectra of fairly simple molecules.

<span class="mw-page-title-main">Residual dipolar coupling</span>

The residual dipolar coupling between two spins in a molecule occurs if the molecules in solution exhibit a partial alignment leading to an incomplete averaging of spatially anisotropic dipolar couplings.

<span class="mw-page-title-main">Zero field NMR</span> Acquisition of NMR spectra of chemicals

Zero- to ultralow-field (ZULF) NMR is the acquisition of nuclear magnetic resonance (NMR) spectra of chemicals with magnetically active nuclei in an environment carefully screened from magnetic fields. ZULF NMR experiments typically involve the use of passive or active shielding to attenuate Earth’s magnetic field. This is in contrast to the majority of NMR experiments which are performed in high magnetic fields provided by superconducting magnets. In ZULF experiments the dominant interactions are nuclear spin-spin couplings, and the coupling between spins and the external magnetic field is a perturbation to this. There are a number of advantages to operating in this regime: magnetic-susceptibility-induced line broadening is attenuated which reduces inhomogeneous broadening of the spectral lines for samples in heterogeneous environments. Another advantage is that the low frequency signals readily pass through conductive materials such as metals due to the increased skin depth; this is not the case for high-field NMR for which the sample containers are usually made of glass, quartz or ceramic.

<span class="mw-page-title-main">Nuclear magnetic resonance</span> Spectroscopic technique based on change of nuclear spin state

Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved; in practical applications with static magnetic fields up to ca. 20 tesla, the frequency is similar to VHF and UHF television broadcasts (60–1000 MHz). NMR results from specific magnetic properties of certain atomic nuclei. Nuclear magnetic resonance spectroscopy is widely used to determine the structure of organic molecules in solution and study molecular physics and crystals as well as non-crystalline materials. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI). The original application of NMR to condensed matter physics is nowadays mostly devoted to strongly correlated electron systems. It reveals large many-body couplings by fast broadband detection and it should not to be confused with solid state NMR, which aims at removing the effect of the same couplings by Magic Angle Spinning techniques.

Electron nuclear double resonance (ENDOR) is a magnetic resonance technique for elucidating the molecular and electronic structure of paramagnetic species. The technique was first introduced to resolve interactions in electron paramagnetic resonance (EPR) spectra. It is currently practiced in a variety of modalities, mainly in the areas of biophysics and heterogeneous catalysis.

Nuclear magnetic resonance crystallography is a method which utilizes primarily NMR spectroscopy to determine the structure of solid materials on the atomic scale. Thus, solid-state NMR spectroscopy would be used primarily, possibly supplemented by quantum chemistry calculations, powder diffraction etc. If suitable crystals can be grown, any crystallographic method would generally be preferred to determine the crystal structure comprising in case of organic compounds the molecular structures and molecular packing. The main interest in NMR crystallography is in microcrystalline materials which are amenable to this method but not to X-ray, neutron and electron diffraction. This is largely because interactions of comparably short range are measured in NMR crystallography.

Nucleic acid NMR is the use of nuclear magnetic resonance spectroscopy to obtain information about the structure and dynamics of nucleic acid molecules, such as DNA or RNA. It is useful for molecules of up to 100 nucleotides, and as of 2003, nearly half of all known RNA structures had been determined by NMR spectroscopy.

Nitrogen-15 nuclear magnetic resonance spectroscopy is a version of nuclear magnetic resonance spectroscopy that examines samples containing the 15N nucleus. 15N NMR differs in several ways from the more common 13C and 1H NMR. To circumvent the difficulties associated with measurement of the quadrupolar, spin-1 14N nuclide, 15N NMR is employed in samples for detection since it has a ground-state spin of ½. Since14N is 99.64% abundant, incorporation of 15N into samples often requires novel synthetic techniques.

<span class="mw-page-title-main">Lyndon Emsley</span> British chemist

David Lyndon Emsley FRSC is a British chemist specialising in solid-state nuclear magnetic resonance and a professor at EPFL. He was awarded the 2012 Grand Prix Charles-Leopold Mayer of the French Académie des Sciences and the 2015 Bourke Award of the Royal Society of Chemistry.

<span class="mw-page-title-main">Cross-polarization</span> Spectroscopy technique

Cross-polarization (CP), originally published as proton-enhanced nuclear induction spectroscopy is a solid-state nuclear magnetic resonance (ssNMR) technique to transfer nuclear magnetization from different types of nuclei via heteronuclear dipolar interactions. The 1H-X cross-polarization dramatically improves the sensitivity of ssNMR experiments of most experiments involving spin-1/2 nuclei, capitalizing on the higher 1H polarisation, and shorter T1(1H) relaxation times. It was developed by Michael Gibby, Alexander Pines and Professor John S. Waugh at the Massachusetts Institute of Technology.

<span class="mw-page-title-main">Spinach (software)</span> Magnetic resonance simulation package

Spinach is an open-source magnetic resonance simulation package initially released in 2011 and continuously updated since. The package is written in Matlab and makes use of the built-in parallel computing and GPU interfaces of Matlab.

References

  1. "National Ultrahigh-Field NMR Facility for Solids" . Retrieved 2014-09-22.
  2. Qian, Chunqi; Pines, Alex; Martin, Rachel W. (2007-09-01). "Design and construction of a contactless mobile RF coil for double resonance variable angle spinning NMR". Journal of Magnetic Resonance. 188 (1): 183–189. Bibcode:2007JMagR.188..183Q. doi:10.1016/j.jmr.2007.06.006. ISSN   1090-7807. PMID   17638585.
  3. Frydman Lucio; Harwood John S (1995). "Isotropic Spectra of Half-Integer Quadrupolar Spins from Bidimensional Magic-Angle Spinning NMR". J. Am. Chem. Soc. 117 (19): 5367–5368. doi:10.1021/ja00124a023.
  4. Massiot D.; Touzo B.; Trumeau D.; Coutures J. P.; Virlet J.; Florian P.; Grandinetti P. J. (1996). "Two-dimensional Magic-Angle Spinning Isotropic Reconstruction Sequences for Quadrupolar Nuclei". Solid-State NMR. 6 (1): 73–83. doi:10.1016/0926-2040(95)01210-9. PMID   8925268.
  5. Duer, Melinda J. (2004). Introduction to solid-state NMR spectroscopy. Oxford, UK: Blackwell. ISBN   1-4051-0914-9. OCLC   53178681.
  6. Duer, Melinda J. (2004). Introduction to solid-state NMR spectroscopy. Oxford, UK: Blackwell. ISBN   1-4051-0914-9. OCLC   53178681.
  7. Hartmann, S. R.; Hahn, E. L. (1962). "Nuclear Double Resonance in the Rotating Frame" (PDF). Phys. Rev. 128 (5): 2042–2053. Bibcode:1962PhRv..128.2042H. doi:10.1103/PhysRev.128.2042.
  8. Stejskal, E.O; Schaefer, Jacob; Waugh, J.S (October 1977). "Magic-angle spinning and polarization transfer in proton-enhanced NMR". Journal of Magnetic Resonance. 28 (1): 105–112. Bibcode:1977JMagR..28..105S. doi:10.1016/0022-2364(77)90260-8.
  9. Haeberlen, U.; Waugh, J. S. (1968-11-10). "Coherent Averaging Effects in Magnetic Resonance". Physical Review. 175 (2): 453–467. Bibcode:1968PhRv..175..453H. doi:10.1103/PhysRev.175.453. ISSN   0031-899X.
  10. Bennett, Andrew E.; Rienstra, Chad M.; Auger, Michèle; Lakshmi, K. V.; Griffin, Robert G. (1995-10-22). "Heteronuclear decoupling in rotating solids". The Journal of Chemical Physics. 103 (16): 6951–6958. Bibcode:1995JChPh.103.6951B. doi:10.1063/1.470372. ISSN   0021-9606.
  11. Fung, B.M.; Khitrin, A.K.; Ermolaev, Konstantin (2000). "An Improved Broadband Decoupling Sequence for Liquid Crystals and Solids". Journal of Magnetic Resonance. 142 (1): 97–101. Bibcode:2000JMagR.142...97F. doi:10.1006/jmre.1999.1896. PMID   10617439.
  12. Thakur, Rajendra Singh; Kurur, Narayanan D.; Madhu, P.K. (2006). "Swept-frequency two-pulse phase modulation for heteronuclear dipolar decoupling in solid-state NMR". Chemical Physics Letters. 426 (4–6): 459–463. Bibcode:2006CPL...426..459T. doi:10.1016/j.cplett.2006.06.007.
  13. Waugh, J. S.; Huber, L. M.; Haeberlen, U. (1968-01-29). "Approach to High-Resolution nmr in Solids". Physical Review Letters. 20 (5): 180–182. Bibcode:1968PhRvL..20..180W. doi:10.1103/PhysRevLett.20.180. ISSN   0031-9007.
  14. Rhim, W‐K.; Elleman, D. D.; Vaughan, R. W. (1973-02-15). "Enhanced resolution for solid state NMR". The Journal of Chemical Physics. 58 (4): 1772–1773. Bibcode:1973JChPh..58.1772R. doi:10.1063/1.1679423. ISSN   0021-9606.
  15. Burum, D.P; Linder, M; Ernst, R.R (July 1981). "Low-power multipulse line narrowing in solid-state NMR". Journal of Magnetic Resonance. 44 (1): 173–188. Bibcode:1981JMagR..44..173B. doi:10.1016/0022-2364(81)90200-6.
  16. Burum, D.P; Linder, M; Ernst, R.R (July 1981). "Low-power multipulse line narrowing in solid-state NMR". Journal of Magnetic Resonance. 44 (1): 173–188. Bibcode:1981JMagR..44..173B. doi:10.1016/0022-2364(81)90200-6.
  17. Lee, Moses; Goldburg, Walter I. (1965-11-15). "Nuclear-Magnetic-Resonance Line Narrowing by a Rotating rf Field". Physical Review. 140 (4A): A1261–A1271. Bibcode:1965PhRv..140.1261L. doi:10.1103/PhysRev.140.A1261.
  18. Sakellariou, Dimitris; Lesage, Anne; Hodgkinson, Paul; Emsley, Lyndon (March 2000). "Homonuclear dipolar decoupling in solid-state NMR using continuous phase modulation". Chemical Physics Letters. 319 (3–4): 253–260. Bibcode:2000CPL...319..253S. doi:10.1016/S0009-2614(00)00127-5.
  19. Paruzzo, Federico M.; Emsley, Lyndon (December 2019). "High-resolution 1H NMR of powdered solids by homonuclear dipolar decoupling". Journal of Magnetic Resonance. 309: 106598. Bibcode:2019JMagR.30906598P. doi: 10.1016/j.jmr.2019.106598 . PMID   31586820. S2CID   203139911.
  20. Zhang, Rongchun; Mroue, Kamal H.; Ramamoorthy, Ayyalusamy (2017-04-18). "Proton-Based Ultrafast Magic Angle Spinning Solid-State NMR Spectroscopy". Accounts of Chemical Research. 50 (4): 1105–1113. doi:10.1021/acs.accounts.7b00082. ISSN   0001-4842. PMC   5828698 . PMID   28353338.
  21. Struppe, Jochem; Quinn, Caitlin M.; Sarkar, Sucharita; Gronenborn, Angela M.; Polenova, Tatyana (2020-01-13). "Ultrafast 1 H MAS NMR Crystallography for Natural Abundance Pharmaceutical Compounds". Molecular Pharmaceutics. 17 (2): 674–682. doi:10.1021/acs.molpharmaceut.9b01157. ISSN   1543-8384. PMC   7307729 . PMID   31891271.
  22. Gullion T.; Schaefer J. (1989). "Rotational-echo double-resonance NMR". J. Magn. Reson. 81 (2): 196–200. doi:10.1016/j.jmr.2011.09.003. PMID   22152360.
  23. Schaefer, Jacob (2007-03-15), "REDOR and TEDOR", in Harris, Robin K. (ed.), Encyclopedia of Magnetic Resonance, Chichester, UK: John Wiley & Sons, Ltd, pp. emrstm0448, doi:10.1002/9780470034590.emrstm0448, ISBN   978-0-470-03459-0 , retrieved 2021-09-13
  24. Linser R.; Fink U.; Reif B. (2008). "Proton-Detected Scalar Coupling Based Assignment Strategies in MAS Solid-State NMR Spectroscopy Applied to Perdeuterated Proteins". J. Magn. Reson. 193 (1): 89–93. Bibcode:2008JMagR.193...89L. doi:10.1016/j.jmr.2008.04.021. hdl: 11858/00-001M-0000-0018-EE69-A . PMID   18462963.
  25. Schanda, P.; Meier, B. H.; Ernst, M. (2010). "Quantitative Analysis of Protein Backbone Dynamics in Microcrystalline Ubiquitin by Solid-State NMR Spectroscopy". J. Am. Chem. Soc. 132 (45): 15957–15967. doi:10.1021/ja100726a. PMID   20977205.
  26. Ishii, Yoshitaka; Wickramasinghe, Ayesha; Matsuda, Isamu; Endo, Yuki; Ishii, Yuji; Nishiyama, Yusuke; Nemoto, Takahiro; Kamihara, Takayuki (2018). "Progress in proton-detected solid-state NMR (SSNMR): Super-fast 2D SSNMR collection for nano-mole-scale proteins". Journal of Magnetic Resonance. 286: 99–109. Bibcode:2018JMagR.286...99I. doi:10.1016/j.jmr.2017.11.011. PMC   6387629 . PMID   29223566.
  27. Lilly Thankamony, Aany Sofia; Wittmann, Johannes J.; Kaushik, Monu; Corzilius, Björn (November 2017). "Dynamic nuclear polarization for sensitivity enhancement in modern solid-state NMR". Progress in Nuclear Magnetic Resonance Spectroscopy. 102–103: 120–195. doi: 10.1016/j.pnmrs.2017.06.002 . PMID   29157490.
  28. Rankin, Andrew G.M.; Trébosc, Julien; Pourpoint, Frédérique; Amoureux, Jean-Paul; Lafon, Olivier (2019-09-01). "Recent developments in MAS DNP-NMR of materials". Solid State Nuclear Magnetic Resonance. 101: 116–143. arXiv: 2007.09954 . doi:10.1016/j.ssnmr.2019.05.009. ISSN   0926-2040. PMID   31189121. S2CID   189814925.
  29. Rankin, Andrew G.M.; Trébosc, Julien; Pourpoint, Frédérique; Amoureux, Jean-Paul; Lafon, Olivier (September 2019). "Recent developments in MAS DNP-NMR of materials". Solid State Nuclear Magnetic Resonance. 101: 116–143. arXiv: 2007.09954 . doi:10.1016/j.ssnmr.2019.05.009. PMID   31189121. S2CID   189814925.
  30. Rossini, Aaron J.; Zagdoun, Alexandre; Lelli, Moreno; Lesage, Anne; Copéret, Christophe; Emsley, Lyndon (2013-09-17). "Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy". Accounts of Chemical Research. 46 (9): 1942–1951. doi:10.1021/ar300322x. ISSN   0001-4842. PMID   23517009.
  31. Perras, Frédéric A.; Kobayashi, Takeshi; Pruski, Marek (2015-07-08). "Natural Abundance 17 O DNP Two-Dimensional and Surface-Enhanced NMR Spectroscopy". Journal of the American Chemical Society. 137 (26): 8336–8339. doi:10.1021/jacs.5b03905. ISSN   0002-7863. OSTI   1227378. PMID   26098846.
  32. Smith, Adam N.; Märker, Katharina; Hediger, Sabine; De Paëpe, Gaël (2019-08-15). "Natural Isotopic Abundance 13 C and 15 N Multidimensional Solid-State NMR Enabled by Dynamic Nuclear Polarization". The Journal of Physical Chemistry Letters. 10 (16): 4652–4662. doi:10.1021/acs.jpclett.8b03874. ISSN   1948-7185. PMID   31361489. S2CID   199000068.
  33. Rossini, Aaron J.; Widdifield, Cory M.; Zagdoun, Alexandre; Lelli, Moreno; Schwarzwälder, Martin; Copéret, Christophe; Lesage, Anne; Emsley, Lyndon (2014-02-12). "Dynamic Nuclear Polarization Enhanced NMR Spectroscopy for Pharmaceutical Formulations". Journal of the American Chemical Society. 136 (6): 2324–2334. doi:10.1021/ja4092038. hdl: 20.500.11850/80771 . ISSN   0002-7863. PMID   24410528.
  34. Laws, David D. Laws; Bitter, Hans-Marcus L.; Jerschow, Alexej (30 August 2002). "Solid-State NMR Spectroscopic Methods in Chemistry". Angewandte Chemie. 41 (17): 3096. doi: 10.1002/1521-3773(20020902)41:17<3096::AID-ANIE3096>3.0.CO;2-X .
  35. Marchetti, Alessandro; Chen, Juner; Pang, Zhenfeng; Li, Shenhui; Ling, Daishun; Deng, Feng; Kong, Xueqian (April 11, 2017). "Understanding Surface and Interfacial Chemistry in Functional Nanomaterials via Solid-State NMR". Advanced Materials. 29 (14): 1605895. doi:10.1002/adma.201605895 . Retrieved 20 December 2023.
  36. McDermott, Ann (June 2009). "Structure and Dynamics of Membrane Proteins by Magic Angle Spinning Solid-State NMR". Annual Review of Biophysics. 38 (1): 385–403. doi:10.1146/annurev.biophys.050708.133719. ISSN   1936-122X. PMID   19245337.
  37. Tycko, Robert (2011-05-05). "Solid-State NMR Studies of Amyloid Fibril Structure". Annual Review of Physical Chemistry. 62 (1): 279–299. Bibcode:2011ARPC...62..279T. doi:10.1146/annurev-physchem-032210-103539. ISSN   0066-426X. PMC   3191906 . PMID   21219138.
  38. Demers, Jean-Philippe; Fricke, Pascal; Shi, Chaowei; Chevelkov, Veniamin; Lange, Adam (December 2018). "Structure determination of supra-molecular assemblies by solid-state NMR: Practical considerations". Progress in Nuclear Magnetic Resonance Spectroscopy. 109: 51–78. Retrieved 20 December 2023.
  39. Chow, W. Y.; Rajan, R.; Muller, K. H.; Reid, D. G.; Skepper, J. N.; Wong, W. C.; Brooks, R. A.; Green, M.; Bihan, D.; Farndale, R. W.; Slatter, D. A. (2014-05-16). "NMR Spectroscopy of Native and in Vitro Tissues Implicates PolyADP Ribose in Biomineralization". Science. 344 (6185): 742–746. Bibcode:2014Sci...344..742C. doi:10.1126/science.1248167. ISSN   0036-8075. PMID   24833391. S2CID   26146114.
  40. New techniques in solid-state NMR. Jacek Klinowski. Berlin: Springer. 2005. ISBN   978-3-540-22168-5. OCLC   56697027.{{cite book}}: CS1 maint: others (link)
  41. Duer, Melinda J. (2015). "The contribution of solid-state NMR spectroscopy to understanding biomineralization: Atomic and molecular structure of bone". Journal of Magnetic Resonance. 253: 98–110. Bibcode:2015JMagR.253...98D. doi:10.1016/j.jmr.2014.12.011. PMID   25797009.
  42. Mohammed, N.R.; Kent, N.W.; Lynch, R.J.M.; Karpukhina, N.; Hill, R.; Anderson, P. (2013). "Effects of Fluoride on in vitro Enamel Demineralization Analyzed by 19F MAS-NMR". Caries Research. 47 (5): 421–428. doi:10.1159/000350171. ISSN   0008-6568. PMID   23712030. S2CID   6854002.
  43. Ferizoli, Bajram; Cresswell-Boyes, Alexander J.; Anderson, Paul; Lynch, Richard J. M.; Hill, Robert G. (2023-05-24). "Effects of fluoride on in vitro hydroxyapatite demineralisation analysed by 19F MAS-NMR". Frontiers in Dental Medicine. 4. doi: 10.3389/fdmed.2023.1171827 . ISSN   2673-4915.
  44. Kricheldorf, H. R.; Müller, D. (1984-11-01). "Secondary structure of peptides 16th. Characterization of proteins by means of13C NMR CP/MAS spectroscopy". Colloid and Polymer Science. 262 (11): 856–861. doi:10.1007/BF01452215. ISSN   1435-1536. S2CID   95774717.
  45. Zhao, Chenhua; Asakura, Tetsuo (2001-12-14). "Structure of Silk studied with NMR". Progress in Nuclear Magnetic Resonance Spectroscopy. 39 (4): 301–352. doi:10.1016/S0079-6565(01)00039-5. ISSN   0079-6565.
  46. Gil, A.M.; Neto, C. Pascoal (1999), "Solid-State Nmr Studies Of Wood And Other Lignocellulosic Materials", Annual Reports on NMR Spectroscopy, vol. 37, Elsevier, pp. 75–117, doi:10.1016/s0066-4103(08)60014-9, ISBN   978-0-12-505337-2 , retrieved 2021-09-13
  47. Quinn, Caitlin M.; Lu, Manman; Suiter, Christopher L.; Hou, Guangjin; Zhang, Huilan; Polenova, Tatyana (2015). "Magic angle spinning NMR of viruses". Progress in Nuclear Magnetic Resonance Spectroscopy. 86–87: 21–40. doi:10.1016/j.pnmrs.2015.02.003. PMC   4413014 . PMID   25919197.
  48. Mandala, Venkata S.; McKay, Matthew J.; Shcherbakov, Alexander A.; Dregni, Aurelio J.; Kolocouris, Antonios; Hong, Mei (2020). "Structure and drug binding of the SARS-CoV-2 envelope protein transmembrane domain in lipid bilayers". Nature Structural & Molecular Biology. 27 (12): 1202–1208. doi:10.1038/s41594-020-00536-8. ISSN   1545-9993. PMC   7718435 . PMID   33177698.
  49. Wang, Tuo; Hong, Mei (2016). "Solid-state NMR investigations of cellulose structure and interactions with matrix polysaccharides in plant primary cell walls". Journal of Experimental Botany. 67 (2): 503–514. doi:10.1093/jxb/erv416. ISSN   0022-0957. PMC   6280985 . PMID   26355148.
  50. Zhao, Wancheng; Fernando, Liyanage D.; Kirui, Alex; Deligey, Fabien; Wang, Tuo (2020). "Solid-state NMR of plant and fungal cell walls: A critical review". Solid State Nuclear Magnetic Resonance. 107: 101660. doi:10.1016/j.ssnmr.2020.101660. PMID   32251983. S2CID   215409770.
  51. Renault, M.; Tommassen-van Boxtel, R.; Bos, M. P.; Post, J. A.; Tommassen, J.; Baldus, M. (2012-03-27). "Cellular solid-state nuclear magnetic resonance spectroscopy". Proceedings of the National Academy of Sciences. 109 (13): 4863–4868. doi: 10.1073/pnas.1116478109 . ISSN   0027-8424. PMC   3323964 . PMID   22331896.
  52. Renault, Marie; Pawsey, Shane; Bos, Martine P.; Koers, Eline J.; Nand, Deepak; Tommassen-van Boxtel, Ria; Rosay, Melanie; Tommassen, Jan; Maas, Werner E.; Baldus, Marc (2012-03-19). "Solid-State NMR Spectroscopy on Cellular Preparations Enhanced by Dynamic Nuclear Polarization". Angewandte Chemie International Edition. 51 (12): 2998–3001. doi:10.1002/anie.201105984. PMID   22298470.
  53. Martínez-Bisbal, M. Carmen; Martí-Bonmatí, Luis; Piquer, José; Revert, Antonio; Ferrer, Pilar; Llácer, José L.; Piotto, Martial; Assemat, Olivier; Celda, Bernardo (2004). "1H and13C HR-MAS spectroscopy of intact biopsy samplesex vivo andin vivo1H MRS study of human high grade gliomas". NMR in Biomedicine. 17 (4): 191–205. doi:10.1002/nbm.888. ISSN   0952-3480. PMID   15229932. S2CID   19939314.
  54. Sarou-Kanian, Vincent; Joudiou, Nicolas; Louat, Fanny; Yon, Maxime; Szeremeta, Frédéric; Même, Sandra; Massiot, Dominique; Decoville, Martine; Fayon, Franck; Beloeil, Jean-Claude (2015). "Metabolite localization in living drosophila using High Resolution Magic Angle Spinning NMR". Scientific Reports. 5 (1): 9872. Bibcode:2015NatSR...5E9872S. doi:10.1038/srep09872. ISSN   2045-2322. PMC   4402646 . PMID   25892587.
  55. Li, Mingyue; Xu, Wei; Su, Yongchao; Su, Yongchao (December 2020). "Solid-state NMR Spectroscopy in Pharmaceutical Sciences". TrAC Trends in Analytical Chemistry. 135 (4): 116152. doi: 10.1016/j.trac.2020.116152 .
  56. Marchetti, Alessandro; Yin, Jinglin; Su, Yongchao; Kong, Xueqian (July 2021). "Solid-state NMR in the Field of Drug Delivery: State of the Art and New Perspectives". Magnetic Resonance Letters. 1 (9): 100003. doi: 10.1016/j.mrl.2021.100003 .
  57. Hoffmann, Herbert; Debowski, Marta; Müller, Philipp; Paasch, Silvia; Senkovska, Irena; Kaskel, Stefan; Brunner, Eike (2012-11-28). "Solid-State NMR Spectroscopy of Metal–Organic Framework Compounds (MOFs)". Materials. 5 (12): 2537–2572. Bibcode:2012Mate....5.2537H. doi: 10.3390/ma5122537 . ISSN   1996-1944. PMC   5449066 .
  58. Blanc, Frédéric; Leskes, Michal; Grey, Clare P. (2013-09-17). "In Situ Solid-State NMR Spectroscopy of Electrochemical Cells: Batteries, Supercapacitors, and Fuel Cells". Accounts of Chemical Research. 46 (9): 1952–1963. doi:10.1021/ar400022u. ISSN   0001-4842. PMID   24041242.
  59. Haber, Shira; Leskes, Michal (2018). "What Can We Learn from Solid State NMR on the Electrode-Electrolyte Interface?". Advanced Materials. 30 (41): 1706496. Bibcode:2018AdM....3006496H. doi:10.1002/adma.201706496. PMID   29889328. S2CID   47012638.
  60. Griffin, John M.; Forse, Alexander C.; Grey, Clare P. (2016). "Solid-state NMR studies of supercapacitors". Solid State Nuclear Magnetic Resonance. 74–75: 16–35. doi:10.1016/j.ssnmr.2016.03.003. PMID   26974032.
  61. Pinto, Moisés L.; Mafra, Luís; Guil, José M.; Pires, João; Rocha, João (2011-03-22). "Adsorption and Activation of CO 2 by Amine-Modified Nanoporous Materials Studied by Solid-State NMR and 13 CO 2 Adsorption". Chemistry of Materials. 23 (6): 1387–1395. doi:10.1021/cm1029563. ISSN   0897-4756.
  62. Schmidt-Rohr, K. (1994). Multidimensional solid-state NMR and polymers. Hans Wolfgang Spiess. London: Academic Press. ISBN   0-12-626630-1. OCLC   31785818.
  63. Del Federico, Eleonora; Centeno, Silvia A; Kehlet, Cindie; Currier, Penelope; Stockman, Denise; Jerschow, Alexej (2009). "Unilateral NMR applied to the conservation of works of art". Analytical and Bioanalytical Chemistry. 396 (1): 213–220. doi:10.1007/s00216-009-3128-7. PMID   19787343. S2CID   206902463.

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