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NMR stands for nuclear magnetic resonance and functions as a powerful tool for chemical characterization. Even though NMR is used mainly for liquids and solutions, technology has progressed to where NMR of solids can be obtained with ease. Aptly named as solid state NMR, the expansion of usable phases has invariably increased our ability to identify chemical compounds. The reason behind difficulties using the solid state lie in the fact that solids are never uniform. When put through a standard NMR, line broadening interactions cannot be removed by rapid molecular motions, which results in unwieldy wide lines which provide little to no useful information. The difference is so staggering that lines broaden by hundreds to thousands of hertz as opposed to less than 0.1 Hz in solution when using an I = 1 / 2 spin nucleus.

A process known as magic angle spinning (MAS), where the sample is tilted at a specific angle, is used in order to overcome line broadening interactions and achieve usable peak resolutions. In order to understand solid state NMR, its history, operating chemical and mathematical principles, and distinctions from gas phase/solution NMR will be explained.


The first notable contribution to what we know today as NMR was Wolfgang Pauli’s ( [link] ) prediction of nuclear spin in 1926. In 1932 Otto Stern ( [link] ) used molecular beams and detected nuclear magnetic moments.

Austrian theoretical physicist Wolfgang Ernst Pauli (1900-1958).
German physicist Otto Stern (1888 - 1969).

Four years later, Gorter performed the first NMR experiment with lithium fluoride (LiF) and hydrated potassium alum (K[Al(SO 4 ) 2 ]•12H 2 O) at low temperatures. Unfortunately, he was unable to characterize the molecules and the first successful NMR for a solution of water was taken in 1945 by Felix Bloch ( [link] ). In the same year, Edward Mills Purcell ( [link] ) managed the first successful NMR for the solid paraffin. Continuing their research, Bloch obtained the 1 H NMR of ethanol and Purcell obtained that of paraffin in 1949. In the same year, the chemical significance of chemical shifts was discovered. Finally, high resolution solid state NMR was made possible in 1958 by the discovery of magic angle spinning.

Swiss physicist Felix Bloch (1905-1983).
American physicist Edward Mills Purcell (1912-1997).

How it works: from machine to graph

NMR spectroscopy works by measuring the nuclear shielding, which can also be seen as the electron density, of a particular element. Nuclear shielding is affected by the chemical environment, as different neighboring atoms will have different effects on nuclear shielding, as electronegative atoms will tend to decrease shielding and vice versa. NMR requires the elements analyzed to have a spin state greater than zero. Commonly used elements are 1 H, 13 C, and 29 Si. Once inside the NMR machine, the presence of a magnetic field splits the spin states ( [link] ).

Spin state splitting as a function of applied magnetic field.

From ( [link] ) we see that a spin state of 1 / 2 is split into two spin states. As spin state value increases, so does the number of spin states. A spin of 1 will have three spin states, 3 / 2 will have four spin states, and so on. However, higher spin states increases the difficulty to accurately read NMR results due to confounding peaks and decreased resolution, so spin states of ½ are generally preferred. The E, or radiofrequency shown in ( [link] ) can be described by [link] , where µ is the magnetic moment, a property intrinsic to each particular element. This constant can be derived from [link] , where ϒ is the gyromagnetic ratio, another element dependent quantity, h is Planck’s constant, and I is the spin.

Questions & Answers

what does nano mean?
Anassong Reply
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s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
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That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
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Mostly, they use nano carbon for electronics and for materials to be strengthened.
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s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
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s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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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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