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Because many solvents also have protons present, their use in obtaining NMR spectra is problematic. The signal due to the protons in a typical organic solvent would be so large that it would swamp any signal due to the sample you want to measure - sort of like trying to see a tiny flashlight in broad daylight outdoors. In order to remedy this problem, one could choose solvents which do not have protons such as CS 2 size 12{ ital "CS" rSub { size 8{2} } } {} or CCl 4 size 12{ ital "CCl" rSub { size 8{4} } } {} ; however, these are not suitable solvents for modern FT spectrometers. A better solution is to use solvents in which the protons have been replaced by deuterium. Such solvents, known as deuterated solvents, have very similar properties to their proton-analogues. Thus deuterated benzene is very similar to normal benzene. While deuterium does have a spin (spin = 1), the frequency at which the deuterium nucleus resonates in a magnetic field is sufficiently different from that of protons so that its presence does not interfere with the detection of proton signals. In reality, not all protons of a solvent are replaced in deuterated solvents such that a residual peak due to the presence of a small quantity of protons can usually be observed. This peak usually serves as a good reference point for determining the chemical shifts of peaks in the sample since the peak locations of common deuterated solvents are well known. One can also add a small amount of TMS [tetramethylsilene, Si ( CH 3 ) 4 size 12{ ital "Si" \( ital "CH" rSub { size 8{3} } \) rSub { size 8{4} } } {} ] to the sample and use its peak to serve as a reference peak as well.

Table 2. Some commonly used deuterated solvents.

d-chloroform CDCl 3 size 12{ ital "CDCl" rSub { size 8{3} } } {}
d 6 size 12{d rSub { size 8{6} } } {} -benzene C 6 D 6 size 12{C rSub { size 8{6} } D rSub { size 8{6} } } {}
d 3 size 12{d rSub { size 8{3} } } {} -acetonitrile CD 3 CN size 12{ ital "CD" rSub { size 8{3} } ital "CN"} {}
d 6 size 12{d rSub { size 8{6} } } {} -acetone CD 3 C ( = O ) CD 3 size 12{ ital "CD" rSub { size 8{3} } C \( =O \) ital "CD" rSub { size 8{3} } } {}
d 4 size 12{d rSub { size 8{4} } } {} -methanol CD 3 OD size 12{ ital "CD" rSub { size 8{3} } ital "OD"} {}
d 8 size 12{d rSub { size 8{8} } } {} -toluene C 6 D 5 CD 3 size 12{C rSub { size 8{6} } D rSub { size 8{5} } ital "CD" rSub { size 8{3} } } {}
d 2 size 12{d rSub { size 8{2} } } {} -dichloromethane CD 2 Cl 2 size 12{ ital "CD" rSub { size 8{2} } ital "Cl" rSub { size 8{2} } } {}
deuterated water D 2 O size 12{D rSub { size 8{2} } O} {}
In order to obtain really high field strengths, special magnets have been built of materials that are kept at liquid helium temperatures such that they become superconducting. Typically field strengths of 200, 300, 400, and 500 MHz are commonly employed. Instruments are even being built with field strengths as high as 900 MHz!!! The choice of field strength depends upon the sample and bigger is usually, but not always, better.

Because the field strengths are so high, it is potentially dangerous for persons with pacemakers to enter into the fringe field region of these magnets. The magnets will also erase the magnetic information stored on IDs and credit cards. The stronger magnets have been known to pull heavy tools up into them if someone with tools walks too close to the magnet. This often causes severe damage to the magnet.

In this set of exercises, we are going to concentrate on 1 H size 12{ {} rSup { size 8{1} } H} {} NMR spectroscopy since it is the most widely used and simplest of the NMR-active nuclei to discuss.

Chemical shift

Since the effect being measured involves the measurement of spin states of a nucleus, the values of Δ size 12{Δ} {} E will be affected by the local magnetic field of a nucleus being examined.

The local magnetic field is, in turn, affected by the chemical environment of the nucleus. Δ size 12{Δ} {} E thus becomes a measure of the chemical environment of the nucleus. Hydrogen atoms bonded to sp 3 size 12{ ital "sp" rSup { size 8{3} } } {} carbon atoms are found in different regions of the NMR spectrum from hydrogen atoms attached to alkene sp 2 size 12{ ital "sp" rSup { size 8{2} } } {} carbon atoms, alkyne sp carbon atoms, and aromatic sp 2 size 12{ ital "sp" rSup { size 8{2} } } {} carbon atoms, oxygen, nitrogen, metals, etc.

Questions & Answers

What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
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.
what is the actual application of fullerenes nowadays?
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.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Chem 215 spring08. OpenStax CNX. Mar 21, 2008 Download for free at http://cnx.org/content/col10496/1.8
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