Nuclear Magnetic Resonance
NMR
,Nuclear Magnetic Resonance (NMR) Spectroscopy is a
powerful and theoretically complex analytical tool which provides
information about the bonding framework of carbon and hydrogen
atoms in the molecule.
It is important to remember that, with NMR, we are performing
experiments on the nuclei of atoms, not the electrons.
NMR spectroscopy is based upon the absorption of radio
waves by certain nuclei in organic molecule when they are
exposed to a strong magnetic field.
, Nuclear spin and the splitting of energy levels in a
magnetic field
Subatomic particles (electrons, protons and neutrons) can be
imagined as spinning on their axes.
In many atoms (such as 12C) these spins are paired against each
other, such that the nucleus of the atom has no overall spin.
However, in some atoms (such as 1H and 13C) the nucleus does
possess an overall spin.
, The rules for determining the net spin of a nucleus are as follows:
1. If the number of neutrons and the number of protons are both
even, then the nucleus has NO spin.
2. If the number of neutrons plus the number of protons is odd,
then the nucleus has a half-integer spin (i.e. 1/2, 3/2, 5/2)
3. If the number of neutrons and the number of protons are both
odd, then the nucleus has an integer spin (i.e. 1, 2, 3)
NMR
,Nuclear Magnetic Resonance (NMR) Spectroscopy is a
powerful and theoretically complex analytical tool which provides
information about the bonding framework of carbon and hydrogen
atoms in the molecule.
It is important to remember that, with NMR, we are performing
experiments on the nuclei of atoms, not the electrons.
NMR spectroscopy is based upon the absorption of radio
waves by certain nuclei in organic molecule when they are
exposed to a strong magnetic field.
, Nuclear spin and the splitting of energy levels in a
magnetic field
Subatomic particles (electrons, protons and neutrons) can be
imagined as spinning on their axes.
In many atoms (such as 12C) these spins are paired against each
other, such that the nucleus of the atom has no overall spin.
However, in some atoms (such as 1H and 13C) the nucleus does
possess an overall spin.
, The rules for determining the net spin of a nucleus are as follows:
1. If the number of neutrons and the number of protons are both
even, then the nucleus has NO spin.
2. If the number of neutrons plus the number of protons is odd,
then the nucleus has a half-integer spin (i.e. 1/2, 3/2, 5/2)
3. If the number of neutrons and the number of protons are both
odd, then the nucleus has an integer spin (i.e. 1, 2, 3)
