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[link] can have E substituted for hν, leading to [link] , which can solve for the NMR resonance frequency (v).

Using the frequency (v), the δ, or expected chemical shift may be computed using [link] .

Delta (δ) is observed in ppm and gives the distance from a set reference. Delta is directly related to the chemical environment of the particular atom. For a low field, or high delta, an atom is in an environment which produces induces less shielding than in a high field, or low delta.

Nmr instrument

An NMR can be divided into three main components: the workstation computer where one operates the NMR instrument, the NMR spectrometer console, and the NMR magnet. A standard sample is inserted through the bore tube and pneumatically lowered into the magnet and NMR probe ( [link] ).

Standard NMR instrument, with main components labeled: (A) bore tube, (B) outer magnet shell, (C) NMR probe.

The first layer inside the NMR ( [link] ) is the liquid nitrogen jacket. Normally, this space is filled with liquid nitrogen at 77 K. The liquid nitrogen reservoir space is mostly above the magnet so that it can act as a less expensive refrigerant to block infrared radiation from reaching the liquid helium jacket.

Diagram of the main layers inside an NMR machine.

The layer following the liquid nitrogen jacket is a 20 K radiation shield made of aluminum wrapped with alternating layers of aluminum foil and open weave gauze. Its purpose is to block infrared radiation which the 77 K liquid nitrogen vessel was unable to eliminate, which increases the ability for liquid helium to remain in the liquid phase due to its very low boiling point. The liquid helium vessel itself, the next layer, is made of stainless steel wrapped in a single layer of aluminum foil, acting once again as an infrared radiation shield. It is about 1.6 mm thick and kept at 4.2 K.

Inside the vessel and around the magnet is the aluminum baffle, which acts as another degree of infrared radiation protection as well as a layer of protection for the superconducting magnet from liquid helium reservoir fluctuations, especially during liquid helium refills. The significance is that superconducting magnets at low fields are not fully submerged in liquid helium, but higher field superconducting magnets must maintain the superconducting solenoid fully immersed in liquid helium The vapor above the liquid itself is actually enough to maintain superconductivity of most magnets, but if it reaches a temperature above 10 K, the magnet quenches. During a quench, the solenoid exceeds its critical temperature for superconductivity and becomes resistive, generating heat. This heat, in turn, boils off the liquid helium. Therefore, a small opening at the very base of the baffle exists as a path for the liquid helium to reach the magnet surface so that during refills the magnet is protected from accidental quenching.

Problems with solid state nmr

The most notable difference between solid samples and solution/gas in terms of NMR spectroscopy is that molecules in solution rotate rapidly while those in a solid are fixed in a lattice. Different peak readings will be produced depending on how the molecules are oriented in the magnetic field because chemical shielding depends upon the orientation of a molecule, causing chemical shift anisotropy. Therefore, the effect of chemical shielding also depends upon the orientation of the molecule with respect to the spectrometer. These counteracting forces are balanced out in gases and solutions because of their randomized molecular movement, but become a serious issue with fixed molecules observed in solid samples. If the chemical shielding isn’t determined accurately, neither will the chemical shifts (δ).

Another issue with solid samples are dipolar interactions which can be very large in solid samples causing linewidths of tens to hundreds of kilohertz to be generated. Dipolar interactions are tensor quantities, which demonstrate values dependent on the orientation and placement of a molecule in reference to its surroundings. Once again the issue goes back to the lattice structure of solids, which are in a fixed location. Even though the molecules are fixed, this does not mean that nuclei are evenly spread apart. Closer nuclei display greater dipolar interactions and vice versa, creating the noise seen in spectra of NMR not adapted for solid samples. Dipolar interactions are averaged out in solution states because of randomized movement. Spin state repulsions are averaged out by molecular motion of solutions and gases. However, in solid state, these interactions are not averaged and become a third source of line broadening.

Magic angle spinning

In order to counteract chemical shift anisotropy and dipolar interactions, magic angle spinning was developed. As discussed above, describing dipolar splitting and chemical shift aniostoropy interactions respectively, it becomes evident that both depend on the geometric factor (3cos 2 θ-1).

If this factor is decreased to 0, then line broadening due to chemical shift anisotropy and dipolar interactions will disappear. Therefore, solid samples are rotated at an angle of 54.74˚, effectively allowing solid samples to behave similarly to solutions/gases in NMR spectroscopy. Standard spinning rates range from 12 kHz to an upper limit of 35 kHz, where higher spin rates are necessary to remove higher intermolecular interactions.

Application of solid state nmr

The development of solid state NMR is a technique necessary to understand and classify compounds that would not work well in solutions, such as powders and complex proteins, or study crystals too small for a different characterization method.

Solid state NMR gives information about local environment of silicon, aluminum, phosphorus, etc. in the structures, and is therefore an important tool in determining structure of molecular sieves. The main issue frequently encountered is that crystals large enough for X-Ray crystallography cannot be grown, so NMR is used since it determines the local environments of these elements. Additionally, by using 13 C and 15 N, solid state NMR helps study amyloid fibrils, filamentous insoluble protein aggregates related to neurodegenerative diseases such as Alzheimer’s disease, type II diabetes, Huntington’s disease, and prion diseases.


  • J. W. Akitt, NMR and Chemistry , 3 rd Edn., Chapman&Hall, London (1992).
  • A. R. Grimmer and B. Blümich, Introduction to Solid-State NMR , Springer-Verlag, Berlin(1994).
  • J. A. Iggo, NMR Spectroscopy in Inorganic Chemistry , Oxford University Press, New York (1999).
  • J. C. C. Chan, Top. Curr. Chem. , 2011, 306 , 47.
  • R. Freeman, Chem Heterocyc Compd , 1995, 31 , 1004-1005.
  • Jeol USA, JEOL Delta-GSX 270 NMR Magnet Destruction ,<http://www.jeolusa.com>
  • University of Pittsburgh, Magnet Safety ,<http://www.ehs.pitt.edu/assets/docs/magnet-safety.pdf>, 2008, (accessed 15 February 2012).

Questions & Answers

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First and foremost -- Wow Rowdy! You have been through a highly difficult situation in your life, hands down. As a wife, I simply cannot phathom nor imagine slightly the feelings and thoughts you bare and I'm sure as these words do not help and hit rewind; my heart and prayers are going out to you-
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Legal psychology
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ana Reply
I think the summation of good and bad deeds you do in your life. Accidentally or otherwise.
Yes. I totally agree.
And if it is bad then the root must have been too.
Yes , In Hinduism we also believe that our parent's Karma also applies to us ! Don't know about that , but it kept people in check .
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karma is the boomerang of your actions. what u put out in the universe u get back
Who is the founder of psychology
Daryl Reply
Wilhelm wundt
Wilhelm Wundt
William wundth
Wilhelm Wundt
and William James
Wilhelm Wundt
Wilhelm Wundt is the founder of structuralism
Yes and also the "Father of Psychology" I think the correct word is Father not Founder.
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Enjoy Reply
George Mason, Penn State, UVA, university of Michigan
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Jerico Reply
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For sure. It depends if you're trying to do an experiment (using statistics probably) or a case study what are you aiming for?
Hello Jerico. Try to opt for something simple and easy to do. I wouls say perhaps study the effects of color on concentration? You could get a group of people and have them take a memory test (you can find some online) in a white room for example. Then have them take another memory test
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but you have to know that a lot of factors will interfere in the performance such as mental state etc so make sure to choose a certain specific population. that's very important
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what are your interests in general?
Althogh I'm persuing botany and engineering.... but I also want to study human behaviour and psychology.... I would like if anyone can share their knowledge with me !!!!
I'm interested on effect of electroconvulsive therapy on people having a depression
What is Electroconvulsive therapy?
Astral Projection
Electroconvulsive therapy (ECT) is a medical treatment that is most commonly used in patients with severe major depression.
What are the expected dutties functions and responsibilities of a head of an agency based on the principles, Practice of industrial psychology?
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what are the psychological characteristics expected from an employee wether regular or occupying a position?
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Source:  OpenStax, Basic knowledge of nuclear magnetic resonance spectroscopy ( nmr ). OpenStax CNX. Jun 07, 2012 Download for free at http://cnx.org/content/col11429/1.1
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